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  • 1.
    Bergström, Gunnel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Subtilisin-catalyzed removal of phosphorylated site of pig liver pyruvate kinase without inactivation of the enzyme1975In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 56, no 2, p. 288-291Article in journal (Refereed)
  • 2.
    Bergström, Gunnel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Proteolytic modification of pig and rat liver pyruvate kinase including the phosphorylatable site1978In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 532, no 2, p. 259-267Article in journal (Refereed)
    Abstract [en]

    The phosphorylated or phosphate-accepting site of pyruvate kinase from pig and rat liver was removed without inactivation by incubation with subtilisin. At different time intervals the subtilisin was inactivated with phenylmethylsulfonyl fluoride and the amount of remaining phosphorylatable or phosphorylated sites of pyruvate kinase estimated by incubation with an excess of [32P]-ATP and protein kinase. It was found that to get the same rate of modification the subtilisin concentration required to modify unphosphorylated pyruvate kinase was approximately ten times higher than that used for removal of the phosphorylated site of phosphorylated site of phosphorylated enzyme. It was shown that the proteolytically-modified pyruvate kinase had an increased apparent Km for phosphoenolpyruvate without a change in V, when compared to unmodified unphosphorylated and phosphorylated pyruvate kinase. The removal of the phosphorylated site was not associated with loss of the allosteric sites for ATP and Fru-1,6-P2. The possibility that phosphorylation of the pyruvate kinase increases its degradation rate in vivo is briefly discussed.

  • 3. Bourgeois, C
    et al.
    Bour, J.B.
    Lidholt, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Gauthray, C
    Pothier, P
    Heparin-like structures on respiratory syncytial virus are involved in its infectivity in vitro.1998In: Journal of Virology, ISSN 0022-538X, E-ISSN 1098-5514, Vol. 72, no 9, p. 7221-7227Article in journal (Refereed)
    Abstract [en]

    Addition of heparin to the virus culture inhibited syncytial plaque formation due to respiratory syncytial virus (RSV). Moreover, pretreatment of the virus with heparinase or an inhibitor of heparin, protamine, greatly reduced virus infectivity. Two anti-heparan sulfate antibodies stained RSV-infected cells, but not noninfected cells, by immunofluorescence. One of the antibodies was capable of neutralizing RSV infection in vitro. These results prove that heparin-like structures identified on RSV play a major role in early stages of infection. The RSV G protein is the attachment protein. Both anti-heparan sulfate antibodies specifically bound to this protein. Enzymatic digestion of polysaccharides in the G protein reduced the binding, which indicates that heparin-like structures are on the G protein. Such oligosaccharides may therefore participate in the attachment of the virus.

  • 4.
    Dahlqvist, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Endogenous substrates of protein kinase in rat liver cell sap under different dietary conditions1978In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 540, no 1, p. 13-23Article in journal (Refereed)
    Abstract [en]

    Liver cell sap from normally fed rats, rats fed with a high-carbohydrate diet and fasted rats was chromatographed on DEAE-cellulose (pH 7.0). The chromatogram from each diet group was analyzed for pyruvate kinase activity and endogenous substrates of cyclic AMP-stimulated protein kinase. The materials were pooled into five phosphorylatable fractions, in each of which phosphate incorporation at 0.1 mM and 1.0 mM [32P]ATP in the presence of cyclic AMP and protein kinase was determined. For characterization of the phosphorylatable components, thin-layer gel chromatography on Sephadex G-200 and polyacrylamide gel electrophoresis in detergent were used for determination of native and minimal molecular weights, respectively. Except for pyruvate kinase, eight components which incorporated at least 0.05 nmol of [32P]phosphate/g of liver were detected. The phosphorylation of four of them was stimulated by cyclic AMP. Their minimal molecular weights were 42000, 21000, 52000 and 49000. The component with a minimal molecular weight of 42000 seemed to have a native molecular weight of 160000. Both the 21000 and the 52000 component had a native molecular weight of about 110000-120000. The protein with a minimal molecular weight of 49000 could not be correlated with certainty to a native molecular weight. The proteins whose phosphorylation was not stimulated by cyclic AMP had minimal molecular weights of 54000, 39000, 34000 and 22000.

  • 5.
    Dahlqvist-Edberg, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Wretborn, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The demonstration in rat liver cell sap of protein kinase and phosphoprotein phosphatase active on fructose-bisphosphatase1982In: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology, ISSN 0167-4838, E-ISSN 1879-2588, Vol. 706, no 2, p. 239-244Article in journal (Refereed)
    Abstract [en]

    A protein kinase active on fructose-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) was demonstrated in rat liver cell sap. The protein kinase activity was stimulated by cyclic AMP and coincided with the activity of cyclic AMP-dependent protein kinase type I. In addition, three different peaks of phosphoprotein phosphatase active on [32P] phosphofructose-bisphosphatase were found on chromatography of rat liver cell sap on a DEAE-cellulose column. These phosphatases needed divalent cations for full activity. 5'-AMP, a negative modulator of fructose-bisphosphatase, had no effect on the phosphorylation-de-phosphorylation reactions of the enzyme. ATP and Ca2+ did not influence the dephosphorylation reaction of fructose-bisphosphatase.

  • 6.
    Edlund, Bror
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Andersson, Jill
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Titanji, Vincent
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Amino acid sequence at the phosphorylated site of rat liver pyruvate kinase1975In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 67, no 4, p. 1516-1521Article in journal (Refereed)
    Abstract [en]

    One dominating peptic phosphopeptide, Asx-Thr-Lys-Gly-Pro-Glx-Ile-Glx-Thr-Gly-Val-Leu-Arg-Arg-Ala-(32P)SerP-Val-Ala-Glx-Leu, was obtained from rat liver pyruvate kinase (type L) phosphorylated by cyclic 3′,5′-AMP-stimulated protein kinase from the same tissue. The sequence around the phosphorylated serine residue is similar to that of a corresponding but smaller peptic phosphopeptide previously isolated from pig liver (type L) pyruvate kinase, Leu-Arg-Arg-Ala-(32P)SerP-Leu.

  • 7.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist-Edberg, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The kinetics of unphosphorylated, phosphorylated and proteolytically modified fructose bisphosphatase from rat liver1981In: Biochimica et Biophysica Acta, ISSN 0005-2744, Vol. 662, no 2, p. 265-270Article in journal (Refereed)
    Abstract [en]

    Phosphorylation of fructose-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) by the catalytic subunit of cyclic AMP-dependent protein kinase from pig muscle decreased the K0.5 for fructose-bisphosphate from 21 to 11 microM. When the phosphorylated fructose-bisphosphatase was treated with trypsin the K0.5 increased to 22 microM. The K0.5 also increased when the phosphoenzyme was treated with a partially purified phosphatase from rat liver. There was no difference between the unphosphorylated and phosphorylated enzyme with respect to pH dependence, the pH optimum being about 7.0 for both. Limited treatment of fructose-bis-phosphatase with subtilisin, which cleaves the enzyme at its unphosphorylatable N-terminal part, increased the pH optimum more than limited treatment with trypsin, which releases the phosphorylated peptide at the C-terminal part of fructose-bisphosphatase. The phosphorylated site on the phosphorylated fructose-bisphosphatase was more easily split off by trypsin treatment than the corresponding unphosphorylated site. The results suggest in addition to the glucagon-induced phosphorylation of fructose-bisphosphatase described by Claus et al. [1] that the phosphorylation-dephosphorylation of fructose-bisphosphatase could be of importance for the hormonal regulation of the enzyme in vivo.

  • 8.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dephosphorylation with alkaline phosphatase of histone and fibrinogen phosphorylated with protein kinase C in vitro.1991In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 96, no 2, p. 95-102Article in journal (Refereed)
    Abstract [en]

    Alkaline phosphatase from calf intestinal mucosa dephosphorylated histone H1 and fibrinogen that had been phosphorylated with protein kinase C. The reaction velocity was dependent on the ionic strength of the buffer; decreasing with increasing concentration. The pH optimum was around 7, which is lower than pH-optima described for other kinds of substrates. (32P) phosphorylated fibrinogen was dephosphorylated about 20 times faster than (32P)phosphohistone on a weight basis and the reaction continued linearily with time for the longest time tested (3 hs) even at 37 degrees C. As alkaline phosphatase is present in the blood the possible physiological significance of the dephosphorylation of phosphofibrinogen is discussed.

  • 9.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Bo
    Laboratory of Immunology, Radiumhospitalet, Montebello, Oslo, Norway.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The quantity of protein-bound (32P)phosphotyrosine in hepatocytes and fibroblasts: The effects of tyrosine protein kinase activating agents1987In: Journal of Biochemistry (Tokyo), ISSN 0021-924X, E-ISSN 1756-2651, Vol. 101, no 4, p. 863-870Article in journal (Refereed)
    Abstract [en]

    Tyrosine protein kinase activities have been demonstrated in transformed and normal cell systems. So far, few data on the quantity of protein-bound phosphotyrosine in intact cells have been published. A knowledge of the stoichiometric increase in phosphotyrosine in cells after hormonal induction could be of interest when evaluating the importance of the tyrosine protein kinase activities found. By the addition of a known amount of unlabeled phosphotyrosine to the precipitated protein of 32P-phosphate-labeled cells it was possible after alkaline hydrolysis to spectrophotometrically follow the phosphotyrosine during consecutive chromatographies of the material. From the specific radioactivity of the purified phosphotyrosine the initial concentration of [32P]phosphotyrosine could be calculated. The method proved to be useful for the determination of [32P]phosphotyrosine is small amounts of cells. The minimum detectable amount of [32P]phosphotyrosine was about 1 pmol, and as an example, only 2.5 X 10(6) fibroblasts were needed. By this method it was shown that platelet-derived growth factor increased protein-bound [32P]phosphotyrosine from 600 to 3,200 pmol/g of fibroblasts, while insulin only increased the [32P]phosphotyrosine from 110 to 120 pmol/g of hepatocytes.

  • 10.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Eller, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Ragnarsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Two methods to avoid the effect of endogenous inhibitors during the assay of protein kinase C activity in tissue extracts.1992In: Preparative Biochemistry, ISSN 0032-7484, Vol. 22, no 2, p. 165-175Article in journal (Refereed)
    Abstract [en]

    Using H1 as substrate the protein kinase C activity of rat liver cell sap was increased about fourfold by treatment with DEAE-cellulose at pH 7.5 at an intermediate ionic strength due to removal of protein inhibitors. The activity of cell sap from rat spleen, brain or muscle was about doubled by the same treatment. In contrast, when a specific synthetic peptide substrate was used the corresponding increase of enzyme activity was not obtained when the inhibitors were removed. This shows that this type of substrates should be preferred for reliable assays of protein kinase C in crude extracts. The possible role of the protein inhibitors for the substrate specificity of protein kinase C is briefly discussed.

  • 11.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Eriksson, Ingrid
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The in vitro modification of phosphorylated pyruvate kinase by a Ca2+-activated protease from rat liver1980In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 34, no 6, p. 419-422Article in journal (Refereed)
    Abstract [en]

    A Ca/+-activated protease from rat liver cell sap was prepared. It was shown to act on rat liver pyruvate kinase that had been phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase, the activity being optimum at neutral pH. The modified pyruvate kinase had the same Vmax as the phosphoenzyme but showed a lower affinity for the substrate phosphoenolpyruvate. The possibility that this proteolytic attack is the step that initiates further degradation in the cell is discussed.

  • 12.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Hermansson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Bergström, Gunnel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Rapid proteolytic removal of phosphopeptides and phosphorylatable sites from proteins in rat liver cell sap1978In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 86, no 2, p. 250-254Article in journal (Refereed)
  • 13.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Jäger, Olle
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Quantification of subnanomolar amounts of phosphate bound to seryl and threonyl residues in phosphoproteins using alkaline hydrolysis and malachite green1993In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 214, no 1, p. 138-141Article in journal (Refereed)
    Abstract [en]

    An assay for protein-bound phosphate with a capacity to determine 100 pmol of phosphate is described. It is based on the combination of two well known methods: the alkaline hydrolysis of phosphate from seryl and threonyl residues in phosphoproteins and the quantification of the released phosphate by the use of malachite green and phosphomolybdate.

  • 14.
    Ekman, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Nilsson, Ewa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Phosphorylation of glucokinase from rat liver in vitro by protein kinase A with a concomitant decrease of its activity1988In: Archives of Biochemistry and Biophysics, ISSN 0003-9861, E-ISSN 1096-0384, Vol. 261, no 2, p. 275-282Article in journal (Refereed)
    Abstract [en]

    Glucokinase, purified from rat liver, was phosphorylated to an extent of 1 mol [32P]-phosphate/mol of enzyme when incubated with [32P]ATP and protein kinase A from pig or rabbit muscle. The phosphate was bound to serine residues. K0.5 increased and Vmax decreased upon phosphorylation. The phosphate group was removed during incubation of the phosphorylated glucokinase with alkaline phosphatase. Enzymatically inactive glucokinase was not phosphorylated by the protein kinase.

  • 15.
    Eller, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Järv, Jaak
    Tartu universitet.
    Toomik, Reet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ragnarsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Substrate specificity of protein kinase C studied with peptides containing D-amino acid residues.1993In: Journal of Biochemistry, ISSN 0021-924X, Vol. 114, no 2, p. 177-180Article in journal (Refereed)
    Abstract [en]

    A set of stereoisomeric nonapeptides KRPSQRAKY with one, two, or all L-amino acid residues replaced by the corresponding D-amino acids, and two analogs with L- and D-threonine instead of serine, were synthesized and tested as substrates for protein kinase C. All of the peptides were phosphorylated by the enzyme. The maximal rate of the reaction with the all-D peptide was more than one order of magnitude lower than that for all-L peptide with serine. The same applied to the peptides with D-Ser or with D-Arg in position +2 with respect to Ser. The Km values for the peptides containing one D-amino acid were close to that for the prototype peptide (53 microM). On the other hand, when two or more D-amino acids were present, the Km value increased considerably. Replacement of serine by threonine also reduced the phosphorylation rate and increased the Km values. One can conclude that the stereospecificity of protein kinase C is much less pronounced than that of protein kinase A, which is in agreement with the less clearly pronounced substrate specificity of the former enzyme.

  • 16.
    Engström, Lorentz
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Pyruvate kinase1987In: The enzymes: Control by Phosphorylation Part B Specific Enzymes (II) Biological Processes, Elsevier, 1987, Vol. 18, p. 47-75Chapter in book (Refereed)
  • 17.
    Eriksson, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Alston-Smith, James
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Endothelial cells release casein kinase II like activity capable of phosphorylating fibrinogen in response to thrombin1993In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 72, no 4, p. 315-320Article in journal (Refereed)
    Abstract [en]

    Rat liver endothelial cells cultivated in the absence of serum and activated with thrombin released up to 10% of the total protein kinase activity into the cell medium using casein or fibrinogen as the phosphate acceptor protein. The activity was partly inhibited by heparin, indicating that it was of the casein kinase II type. The release of kinase started directly after the addition of thrombin (2 NIH U/ml) to the media with two maxima; one after about 10 min and the second after around 30 min. The phosphorylating activity of media from cells incubated for longer times was less dependent on thrombin-induction which probably indicated the start of destruction of the cells. The results reported suggest that phosphorylation of fibrinogen could occur in the blood under acute phase conditions.

  • 18.
    Forsberg, Per-Olof
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Martin, Steven
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Nilsson, Bo
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Nilsson, Ulf
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    In vitro phosphorylation of human complement factor C3 by protein kinase A and protein kinase C: Effects on the classical and alternative pathways1990In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 265, no 5, p. 2941-2946Article in journal (Refereed)
    Abstract [en]

    Complement factor C3, recently found to contain covalently bound phosphate, was phosphorylated in vitro by cyclic AMP-dependent protein kinase (protein kinase A) and Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C). Both protein kinases phosphorylated the same serine residue(s) located in the C3a portion of the alpha-chain. In addition, protein kinase C phosphorylated the beta-chain to a lesser extent. Protein kinase A gave a maximal incorporation of 1 mol of phosphate/mol of C3 while that value with protein kinase C was 1.5 mol of phosphate/mol of C3. The velocity in pmol of [32P]phosphate/(min x unit kinase) was 20 times higher for protein kinase C than for protein kinase A although a 10 times lower ratio of protein kinase to C3 was used in the former case. The apparent Kmfor C3 was 2.6 µM when protein kinase C was used. The phosphorylated C3 was found to be more resistant to partial degradation by trypsin than unphosphorylated C3. It was also found that phosphorylation of C3 in the C3a portion of the alpha-chain inhibited both the classical and alternative complement activation pathways on an approximately stoichiometric basis.

  • 19.
    Gullberg, Donald
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Tingström, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Thuresson, A C
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Olsson, L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Terracio, L
    Borg, T K
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Beta 1 integrin-mediated collagen gel contraction is stimulated by PDGF1990In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 186, no 2, p. 264-272Article in journal (Refereed)
  • 20. Hogevik, H
    et al.
    Söderquist, B
    Tung, H S
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Olaisson, L
    Westberg, A
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Rydén, Cecilia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
    Tarkowski, A
    Andersson, R
    Virulence factors of Staphylococcus aureus strains causing infective endocarditis: a comparison with strains from skin infections1998In: APMIS: Acta pathologica, microbiologica et immunologica Scandinavica. Supplementum, ISSN 0903-465X, E-ISSN 1600-5503, Vol. 106, no 9, p. 901-908Article in journal (Refereed)
    Abstract [en]

    The objective was to study potential bacterial virulence factors in S. aureus endocarditis. S. aureus strains isolated from patients with well-classified episodes of infective endocarditis (IE) (n=26) were compared with control S. aureus strains from consecutive patients with skin infections (n=30). The potential virulence factors studied were Staphylococcal enterotoxin A-D (SEA, SEB, SEC, SED) and toxic shock syndrome toxin-1 (TSST-1) production and binding capacity to the extracellular matrix proteins: fibronectin, collagen type I, collagen type II and bone sialoprotein (BSP). None of the potential virulence factors studied was more prevalent among the IE strains. BSP binding was more often found in the control group with skin infections. Endocarditis patients with previous damage of the heart valves were more often infected by strains not producing any enterotoxin. No correlation was found between the potential bacterial virulence factors studied and IE. Concerning the toxins known to act as superantigens (SEA-E and TSST-1), the tendencies in this and other studies indicate that a larger study group might identify them as pathogenic factors in a subgroup of staphylococcal endocarditis

  • 21.
    Järv, Jaak
    et al.
    Tartu universitet.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Phosphorylation of Sepharose-coupled peptides by protein kinase A1996In: Bioorganic chemistry (Print), ISSN 0045-2068, Vol. 24, no 1, p. 1-9Article in journal (Refereed)
    Abstract [en]

    The kinetics of phosphorylation of the Sepharose-coupledpeptide RRASVA by catalytic subunit of proteinkinaseA, and diastereomers of this peptide, containingd-amino acids successively in each position, were studied. Coupling of these peptides with the amino and carboxyl termini to CH- and AH-Sepharoses had similar effects on the phosphorylation reaction, increasing theKmand decreasing theVvalues, respectively. The diastereomeric peptides were also phosphorylated by the enzyme and the rate of this reaction depended on the position of substitution ofl-amino acids with theird-analogs. However, this dependence was much less pronounced if compared with stereoselectivity of the enzyme in reactions with these peptides in solution: theKmvalues for the Sepharose-coupledpeptides were almost insensitive to the replacement ofl-amino acids withd-analogs and moderate stereoselectivity was revealed in the maximal velocity of the reaction. The Sepharose-coupledpeptide containingd-serine was also phosphorylated by proteinkinaseA while the same peptide in solution did not interact with the enzyme. Consequently, the polymer, enveloping the phosphorylatable peptide, may remarkably influence the recognition of the reaction site, altering both V and Km values.

  • 22.
    Järv, Jaak
    et al.
    Tartu universitet.
    Sak, Katrin
    Tartu universitet.
    Eller, Marika
    Tartu universitet.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Åke
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Quantitative structure-activity relationships in protein kinase C reaction with synthetic peptides derived from myelin basic protein1996In: Bioorganic chemistry (Print), ISSN 0045-2068, Vol. 24, no 2, p. 159-168Article in journal (Refereed)
    Abstract [en]

    A set of peptides, Lys-Arg-Pro-Ser-X-Arg-Ala-Lys-Ala, where X stands for Ala, Val, Leu, Ile, Phe, Pro, Lys, Arg, Asp, Glu, Asn, Gln, and His, was synthesized and the kinetics of their phosphorylation by protein kinase C was studied. All compounds, except the peptide with Pro at the position X, were effectively phosphorylated by this enzyme, and for these substrates the kinetic constantsKm, maximal velocity constantsV, and second-order rate constantskIIwere determined. The data were analyzed by means of quantitative structure–activity relationships, taking into account hydrophobicity of the variable amino acids, bulkiness of their side groups quantified by molecular refractivity constants MR, and ionic status of these substituents by using an independent variable +1 for cationic, −1 for anionic, and 0 for nonionic substituents. These structural factors influenced theKmvalues, while the maximal velocity of phosphorylation depended mostly on the ionic status of the variable amino acid. The latter effect seems to characterize electrostatic interaction between the substrate molecule and some negative charge located in the enzyme active center.

  • 23. Kitagawa, H
    et al.
    Tanaka, Y
    Tsuchida, K
    Goto, F
    Ogawa, T
    Lidholt, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    GalNAc Transfer to the Common Carbohydrate-ProteinLinkage Region of Sulfated Glycosaminoglycans.Identification of UDP-GalNAc: GlcA-Oligosaccharidect-N-Acetylgalactosaminyltransferase in Bovine Serum1995In: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 12, no 4, p. 466-Article in journal (Other academic)
  • 24. Kitagawa, H
    et al.
    Tanaka, Y
    Tsuchida, K
    Goto, F
    Ogawa, T
    Lidholt, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Sugahara, K
    N-acetylgalactosamine (GalNAc) transfer to the common carbohydrate-protein linkage region of sulfated glycosaminoglycans: identification of UDP-GaINAc:chondro oligosaccharide aNacetylgalactosaminyltransferase in fetal bovine serum1995In: The Journal of Biological Chemsitry, ISSN 0021-9258, Vol. 270, no 38, p. 22190-22195Article in journal (Refereed)
    Abstract [en]

    During the course of a study to elucidate the role ofmodification of the common polysaccharide-protein linkagestructure, GlcAb1–3Galb1–3Galb1–4Xylb1-O-Ser, inbiosynthetic sorting mechanisms of the different sulfatedglycosaminoglycan chains, a novel N-acetylgalactosamine(GalNAc) transferase was discovered in fetalbovine serum. The enzyme catalyzed the transfer of[3H]GalNAc from UDP-[3H]GalNAc to linkage tetrasaccharideand hexasaccharide serines synthesized chemicallyand to various regular oligosaccharides containingterminal D-glucuronic acid (GlcA), which were preparedfrom chondroitin and chondroitin sulfate using testicularhyaluronidase digestion. The labeled products obtainedwith the linkage tetra- and hexasaccharideserines and with the tetrasaccharide (GlcAb1–3GalNAc)2were resistant to digestion with chondroitinase AC-IIand b-N-acetylhexosaminidase but sensitive to a-Nacetylgalactosaminidasedigestion, indicating that theenzyme is an a-N-acetylgalactosaminyltransferase. Thisfinding is in contrast to that of Rohrmann et al. (Rohrmann,K., Niemann, R., and Buddecke, E. (1985) Eur. J.Biochem., 148, 463–469), who reported that a correspondingproduct was susceptible to digestion with b-Nacetylhexosaminidase.The presence of a sulfate groupat C4 of the penultimate GalNAc or Gal units markedlyinhibited the transfer of GalNAc to the terminal GlcA,while a sulfate group at C6 of the GalNAc had little effecton the transfer. Moreover, a slight but significant transferof [3H]GalNAc was observed to an oligosaccharidecontaining terminal 2-O-sulfated GlcA as acceptor,whereas no incorporation was detected into oligosaccharidescontaining terminal unsaturated or 3-O-sulfatedGlcA units. These results suggest that this novelserum enzyme is a UDP-GalNAc:chondro-oligosaccharidea1–3- or 1–4-N-acetylgalactosaminyltransferase.

  • 25.
    Laurent, Torvald C.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lilja, K.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Brunnberg, L.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström-Laurent, A.
    Laurent, U. B.
    Lindqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Murata, K.
    Ytterberg, D.
    Urinary excretion of hyaluronan in man1987In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 47, no 8, p. 793-799Article in journal (Refereed)
    Abstract [en]

    A specific assay for hyaluronan (hyaluronic acid) has been applied to the determination of the polysaccharide in urine. The excretion in 22 healthy subjects was 330 micrograms/24 h (SD 77). The excretion was correlated with body weight and was therefore somewhat higher in males than in females. The molecular weight of the main fraction of urinary hyaluronan was in the range of 4000 to 12,000 in accordance with the hypothesis that it originates from blood and arises by glomerular filtration. A small fraction was of higher molecular weight and could have been produced in the urinary tract. Hyaluronan in male and female urine displayed the same molecular weight distributions. Patients with rheumatoid arthritis and primary biliary cirrhosis showed a two-fold and three-fold increase, respectively, of hyaluronan in urine with concurrently high levels of the polysaccharide in serum. A patient with Werner's syndrome displayed a ten-fold increase of the polysaccharide in both serum and urine.

  • 26.
    Lidholt, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Erikssson, I
    Kjellen, L
    Heparin proteoglycans synthesized by mouse mastocytoma contain chondroitin sulphate.1995In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 311, no 1, p. 233-238Article in journal (Refereed)
    Abstract [en]

    Proteoglycans (PGs), biosynthetically labelled with [S-35]sulphate, were isolated from mouse mastocytoma tissue. Chromatography on antithrombin (AT)-Sepharose resulted in the separation of the S-35-labelled PGs into three fractions: PGs with no affinity for the gel (NA-PGs), PGs with low affinity (LA-PGs), and PGs with high affinity (HA-PGs) for antithrombin. Whereas NA-PGs contained almost exclusively chondroitin sulphate (CS), the AT-binding PGs contained 80-85% heparin and 15-20% CS. [S-35]CS-containing macromolecules obtained from the HA-PG fraction after removal of the heparin polysaccharide chains were rechromatographed on AT-Sepharose. A majority of these S-35-labelled macromolecules no longer showed affinity for AT. These experiments indicate that the [S-35]CS recovered in the AT-binding PGs is present in hybrid PGs. Polysaccharide chain-length determination demonstrated that the heparin chains were somewhat larger (M(r) similar to 30000) than the CS chains in the NA-PGs (M(r) similar to 25000). CS chains in the hybrid PGs were slightly smaller (M(r) similar to 20000). Characterization of the sulphated CS disaccharides from NA- and HA-PGs showed that they contained similar amounts (20 %) of disulphated disaccharides of [GlcA-GalNAc(4,6-di-OSO3)] type. The monosulphated CS-disaccharides were O-sulphated at C-4 of the galactosamine units. Analysis by gel chromatography of the [S-35]CS components isolated from HA-PGs after heparinase treatment showed that a major portion of these contained one CS chain only. Calculations of the number of CS and heparin chains in AT-binding PGs, based on polysaccharide composition and polysaccharide chain length, indicate that all heparin-containing PGs are hybrids.

  • 27.
    Lidholt, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Fjelstad, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Biosynthesis of the E.coli K4 capsule polysaccharide: a parallel system for studies of glycosyltransferases in chondroitin formation1997In: The Journal of Biological Chemistry, ISSN 0021-9258, Vol. 272, no 5, p. 2682-2687Article in journal (Refereed)
    Abstract [en]

    Escherichia coli K4 bacteria synthesize a capsule polysaccharide(GalNAc-GlcA(fructose))n with the carbohydratebackbone identical to chondroitin. GlcA- andGalNAc-transferase activities from the bacterial membranewere assayed with acceptors derived from thecapsule polysaccharide and radiolabeled UDP-[14C]GlcAand UDP-[3H]GalNAc, respectively. It was shown thatdefructosylated oligosaccharides (chondroitin) couldserve as substrates for both the GlcA- and the GalNActransferases.The radiolabeled products were completelydegraded with chondroitinase AC; the [14C]GlcAunit could be removed by b-D-glucuronidase, and the[3H]GalNAc could be removed by b-N-acetylhexosaminidase.A fructosylated oligosaccharide acceptor testedfor GlcA-transferase activity was found to be inactive.These results indicate that the chain elongation reactionof the K4 polysaccharide proceeds in the same wayas the polymerization of the chondroitin chain, by theaddition of the monosaccharide units one by one to thenonreducing end of the polymer. This makes the biosynthesisof the K4 polysaccharide an interesting parallelsystem for studies of chondroitin sulfate biosynthesis.In the biosynthesis of capsule polysaccharides from E.coli, a similar mechanism has earlier been demonstratedfor polysialic acid (NeuNAc)n (Rohr, T. E., and Troy, F. A.(1980) J. Biol. Chem. 255, 2332–2342) and for the K5 polysaccharide(GlcAb1–4GlcNAca1–4)n (Lidholt, K., Fjelstad,M., Jann, K., and Lindahl, U. (1994) Carbohydr. Res.255, 87–101). In contrast, chain elongation of hyaluronan(GlcAb1–3GlcNAcb1–4)n is claimed to occur at the reducingend (Prehm, P. (1983) Biochem. J. 211, 181–189).

  • 28.
    Lidholt, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Fjelstad, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Biosynthesis of the Escherichia coli K4 capsule polysaccharide: a parallel system for studies of glycosyltransferases in chondroitin formation.1997In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 272, no 5, p. 2682-2687Article in journal (Refereed)
    Abstract [en]

    Escherichia coli K4 bacteria synthesize a capsule polysaccharide (GalNAc-GlcA(fructose))(n) with the carbohydrate backbone identical to chondroitin. GlcA- and GalNAc-transferase activities from the bacterial mem brane were assayed with accepters derived from the capsule polysaccharide and radiolabeled UDP-[C-14]GlcA and UDP-[H-3]GalNAc, respectively. It was shown that defructosylated oligosaccharides (chondroitin) could serve as substrates for both the GlcA- and the GalNAc-transferases. The radiolabeled products were completely degraded with chondroitinase AC; the [C-14]GlcA unit could be removed by beta-D-glucuronidase, and the [H-3]GalNAc could be removed by beta-N-acetylhexosaminidase. A fructosylated oligosaccharide acceptor tested for GlcA-transferase activity was found to be inactive. These results indicate that the chain elongation reaction of the K4 polysaccharide proceeds in the same way as the polymerization of the chondroitin chain, by the addition of the monosaccharide units one by one to the nonreducing end of the polymer. This makes the biosynthesis of the K4 polysaccharide an interesting parallel system for studies of chondroitin sulfate biosynthesis. In the biosynthesis of capsule polysaccharides from E. coli, a similar mechanism has earlier been demonstrated for polysialic acid (NeuNAc)(n) (Rohr, T. E., and Troy, F. A. (1980) J. Biol. Chem. 255, 2332-2342) and for the K5 polysaccharide (GlcA beta 1-4GlcNAc alpha 1-4)(n) (Lidholt, K., Fjelstad, M., Jann, K., and Lindahl, U. (1994) Carbohydr. Res. 255, 87-101). In contrast, chain elongation of hyaluronan (GlcA beta 1-3GlcNAc beta 1-4)(n) is claimed to occur at the reducing end (Prehm, P. (1983) Biochem. J. 211, 181-189).

  • 29.
    Lidholt, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Fjelstad, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Goto, F
    Ogawa, T
    Kitagawa, H
    Sugahara, K
    Assessment of glycosaminoglycan-protein linkage tetrasaccharides as acceptors for GalNAc- and GlcNAc-transferases from mouse mastocytoma.1997In: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 14, no 6, p. 737-742Article in journal (Refereed)
    Abstract [en]

    Two glycosaminoglycan-protein linkage tetrasaccharide-serine compounds, GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl beta 1-O-Ser and GlcA beta 1-3Gal(4-O-sulfate)beta 1-3Gal beta 1-4Xyl beta 1-O-Ser, were tested as hexosamine accepters, using UDP-[H-3]GlcNAc and UDP-[H-3]GalNAc as sugar donors, and solubilized mouse mastocytoma microsomes as enzyme source. The nonsulfated Ser-tetrasaccharide was found to function as an acceptor for a GalNAc residue, whereas the Ser-tetrasaccharide containing a sulfated galactose unit was inactive. Characterization of the radio-labelled product by digestion with alpha-N-acetylgalactosaminidase and beta-N-acetylhexosaminidase revealed that the [H-3]GalNAc unit was alpha-linked, as in the product previously synthesized using serum enzymes, and not beta-linked as found in the chondroitin sulfate polymer. Heparan sulfate/heparin biosynthesis could not be primed by either of the two linkage Ser-tetrasaccharides, since no transfer of [H-3]GlcNAc from UDP-[H-3]GlcNAc could be detected. By contrast, transfer of a [H-3]GlcNAc unit to a [GlcA beta 1-4GlcNAca1-4](2)-GlcA beta 1-4-aMan hexasaccharide acceptor used to assay the GlcNAc transferase involved in chain elongation, was readily detected. These results are in agreement with the recent proposal that two different N-acetylglucosaminyl transferases catalyse the biosynthesis of heparan sulfate. Although the mastocytoma system contains both the heparan sulfate/heparin and chondroitin sulfate biosynthetic enzymes the Ser-tetrasaccharides do not seem to fulfil the requirements to serve as accepters for the first HexNAc transfer reactions involved in the formation of these polysaccharides.

  • 30.
    Lind, Thomas
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lidholt, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Purification of the protein catalysing both GlcNAc and GlcA transfer in the chain elongation reaction of heparin/heparan sulfate1995In: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 12, no 4, p. 466-467Article in journal (Refereed)
  • 31.
    Lindqvist, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Engström-Laurent, A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Laurent, U.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Nyberg, A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Internal Medicine.
    Björklund, U.
    Eriksson, H.
    Pettersson, R.
    Tengblad, A.
    The diurnal variation of serum hyaluronan in health and disease1988In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 48, no 8, p. 765-770Article in journal (Refereed)
    Abstract [en]

    The variation of the serum concentration of hyaluronan during the day and between days has been investigated. In a group of healthy volunteers, the mean hyaluronan level was very stable over time except for a moderate but significant elevation after rising from bed in the morning. Patients with rheumatoid arthritis showed markedly increased hyaluronan concentrations 0.5-2 h after leaving bed. Patients with primary biliary cirrhosis exhibited high and rather constant levels during the day. A reference group of hospitalized patients with other diseases did not show any diurnal variation. The best reproducibility in hyaluronan determinations is obtained if specimens are taken before the subjects rise from bed or a few hours later, i.e. after the morning elevation of serum hyaluronan has subsided. In rheumatoid arthritis valuable information can be obtained by repeated sampling during the morning hours.

  • 32.
    Ljungström, Olle
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Glucagon-induced phosphorylation of pyruvate kinase (type L) in rat liver slices1977In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 78, no 4, p. 1147-1155Article in journal (Refereed)
    Abstract [en]

    The effect of glucagon on the phosphorylation of pyruvate kinase in 32P-labelled slices from rat liver was investigated. Pyruvate kinase was isolated by immunoadsorbent chromatography. The enzyme was partially phosphorylated in the absence of added hormone (0.2 mol of phosphate/mol of enzyme subunit). Upon incubation with 10−7 M glucagon, the incorporation of [32P]phosphate was 0.6–0.7 mol/mol of enzyme subunit. Concomitantly, the concentration of intracellular cyclic 3′,5′-AMP increased from 0.3 to 3.2 μM. The phosphorylation inhibited the enzyme activity at low concentrations of phosphoenolpyruvate (60% at 0.5 mM). Almost maximal phosphorylation of the enzyme was reached within 2 min after the addition of glucagon. The concentration of hormone giving half maximal effect on the pyruvate kinase phosphorylation was about 7×10−9M. The inactivation of the enzyme paralleled the increase in phosphorylation. It is concluded that pyruvate kinase is phosphorylated in the intact liver cell.

  • 33. Loog, Mart
    et al.
    Eller, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Eriksson, Stefan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Järv, Jaak
    Tartu universitet.
    Ragnarsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Toomik, Reet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Comparision of substrate specificities of protein kinases A and C based on peptide substrates1994In: Bioorganic chemistry (Print), ISSN 0045-2068, Vol. 22, no 3, p. 328-336Article in journal (Refereed)
    Abstract [en]

    Peptides, obtained by gradual removal of amino acids from both ends of pEKRPSQRSKYL, and stereoisomeric nonapeptides KRPSQRAKY with one D-amino acid residue successively in each position, were tested as substrates for protein kinase A, All these compounds were phosphorylated but at quite different rates by the enzyme. Comparison of the kinetic data with the appropriate results for protein kinase C, measured earlier, was used to analyze and compare the specificity determining factors of these enzymes. The analysis of the cross-specificity points to the possibility that only a short part, mainly the sequence of 1 to 2 amino acids around the phosphorylatable serine residue, is important for differentiation of substrates by these enzymes, while the remaining part of the peptide structure has similar influence on their reactivity in the case of these two protein kinases. Thus, the active center of these enzymes can be conventionally divided into two parts, which are responsible for selectivity and effectiveness of the phosphorylation reaction, respectively.

  • 34.
    Martin, Steven C.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    In vitro phosphorylation of serum albumin by two protein kinases:  a potential pitfall in protein phosphorylation reactions1986In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 154, no 2, p. 395-399Article in journal (Refereed)
    Abstract [en]

    Bovine albumin was phosphorylated by both cAMP-dependent protein kinase and casein kinase I to a significant extent. Other albumins were also tested and it was found that the extent of phosphorylation varied with the species of origin of the albumin, but was between 1 and 3 mol phosphate per mole albumin for the cAMP-dependent protein kinase-catalyzed reactions. The phosphorylation occurred at and above pH 7.5 and required the presence of thiol reagents. Phosphoamino acid analyses of bovine albumin showed that it was phosphorylated on at least two serine residues. The phosphorylation could not be demonstrated in vivo.

  • 35.
    Martin, Steven
    et al.
    Institute of Biochemistry, Glasgow Royal Infirmary, Glasgow, Scotland.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Forsberg, Per-Olof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ersmark, Hans
    Samariterhemmet Uppsala.
    Increased phosphate content of fibrinogen  in vivo correlates with alteration in fibrinogen behaviour1992In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 68, no 6, p. 467-473Article in journal (Refereed)
    Abstract [en]

    Fibrinogen was purified from five patients admitted for hip-replacement surgery the day before (day 0), the day after (day 2) and and one week after the operation (day 8). The behaviour of each patient's three fibrinogens was compared in thrombin gelation assays and plasmin degradation experiments to investigate whether the reported increase in protein-bound phosphate at day 2 and day 8 had any effect on the functional behaviour of fibrinogen as has been demonstrated in vitro. It was found that the thickness of the fibrin fibres produced by thrombin increased markedly at day 2 and declined thereafter. Susceptibility to plasmin appeared to decrease post-operatively by 50% and remained at that level on day 8 despite the phosphate content returning to normal. This has also been shown for fibrinogen phosphorylated in vitro. We conclude, after testing the fibrinogens with and without alkaline phosphatase pretreatment, that our data most resemble the published findings for in vitro phosphorylation of fibrinogen by casein kinase II.

  • 36.
    Muszynska, Grazyna
    et al.
    Polish Academy of Science, Warsawa.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Phospholipid- dependent and EGTA-inhibited protein kinase from maize seedlings1993In: Biochemistry and Molecular Biology International, ISSN 1039-9712, Vol. 30, no 5, p. 849-860Article in journal (Refereed)
    Abstract [en]

    Chromatography of a maize seedling extract on DEAE-cellulose, followed by Octyl-Sepharose yielded a fraction with protein kinase activity which was stimulated by phosphatidylserine plus diolein. The activity was not enhanced by calcium ions but was inhibited by chelating agents and could then be restored by the addition of calcium ions. All these facts indicated that the maize protein kinase was similar to mammalian protein kinase C. The maize enzyme phosphorylated myelin basic protein (MBP) and histone H1, but the MBP-peptide4-14 and protamine were poor substrates for the enzyme. Further purification of the enzyme fraction followed by phosphorylation and SDS-polyacrylamide gel electrophoresis, revealed two labeled bands of Mw 59 and 83 kDa the former of which probably being the protein kinase C.

  • 37.
    Nilsson Ekdahl, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Effects of epinephrine, glucagon and insulin on the activity and degree of phosphorylation of fructose-1,6-bisphosphatase in cultured hepatocytes.1987In: Biochimica et Biophysica Acta. Molecular Cell Research, ISSN 0167-4889, E-ISSN 1879-2596, Vol. 929, no 3, p. 318-326Article in journal (Refereed)
    Abstract [en]

    The effects of epinephrine, glucagon and insulin on the activity and degree of phosphorylation of fructose-1,6-bisphosphatase in isolated hepatocytes maintained in cell culture for 24 h were investigated. Epinephrine caused a rapid decrease in the apparent Km monitored as the activity ratio between the activity at 12.5 and 83 microM fructose-1,6-bisphosphate, reaching a maximum after 5 min. Glucagon caused a slower and less pronounced activation, and insulin caused an equally slow increase in Km. The effect of epinephrine and glucagon was completely reciprocated by insulin and the action of insulin was totally erased by the other two. Glucagon stimulated the incorporation of [32P]phosphate into fructose-1,6-bisphosphatase from about 2.5 to 4.2 mol/mol enzyme and epinephrine to 3.5 mol/mol. The effect of the two hormones acting together was cumulative. Insulin brought about a decrease in the degree of phosphorylation to 2.0 mol/mol. The effect of epinephrine was shown to be caused by the beta-receptors, since it was completely blocked by propanolol (a beta-antagonist) and remained unaffected by the presence of phentolamine (an alpha-antagonist).

  • 38.
    Nilsson Ekdahl, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Fructose-1,6-bisphosphatase from rat liver: A comparision of the kinetics of the unphosphorylated enzyme and the enzyme phosphorylated with cyclic AMP-dependent protein kinase1985In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 260, no 26, p. 14173-14179Article in journal (Refereed)
    Abstract [en]

    A purification procedure for rat hepatic fructose-1,6-bisphosphatase, described earlier, has been improved, resulting in an enzyme preparation with a neutral pH optimum and with both phosphorylatable serine residues present. The subunit Mr was 40,000. Phosphorylation in vitro with cyclic AMP-dependent protein kinase resulted in the incorporation of 1.4 mol of phosphate/mol of subunit and led to an almost 2-fold decrease in apparent Km for fructose-1,6-bisphosphate. In contrast to yeast fructose-1,6-bisphosphatase, fructose-2,6-bisphosphate had no effect on the rate of phosphorylation or dephosphorylation of the intact enzyme. The effects of the composition of the assay medium, with regard to buffering substance and Mg2+ concentration, on the apparent Km values of phosphorylated and unphosphorylated enzyme were investigated. The kinetics of phosphorylated and unphosphorylated fructose-1,6-bisphosphatase were studied with special reference to the inhibitory effects of adenine nucleotides and fructose-2,6-bisphosphate. Unphosphorylated fructose-1,6-bisphosphatase was more susceptible to inhibition by both AMP and fructose 2,6-bisphosphate than phosphorylated enzyme, at high and low substrate concentrations. Both ATP and ADP had a similar effect on the two enzyme forms, ADP being the more potent inhibitor. Finally, the combined effect of several inhibitors at physiological concentrations was studied. Under conditions resembling the gluconeogenic state, phosphorylated fructose-1,6-bisphosphatase was found to have twice the activity of the unphosphorylated enzyme.

  • 39.
    Nilsson Ekdahl, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Hepatic L -type pyruvate kinase: Separation of unphosphorylated, phosphorylated and proteolytically modified in vivo forms1984In: Journal of Biochemistry (Tokyo), ISSN 0021-924X, E-ISSN 1756-2651, Vol. 95, no 4, p. 917-924Article in journal (Refereed)
    Abstract [en]

    After partial chromatographic purification of rat liver cell sap on DEAE-cellulose, including the removal of type M2 pyruvate kinase, different forms of type L pyruvate kinase were separated by chromatofocusing. Three fractions of pyruvate kinase activity were found, eluting at pH 5.0, 5.2, and 5.3, respectively. The first one was identified as phosphorylated and the second one as unphosphorylated pyruvate kinase. There were strong indications that the third fraction represented a proteolytically modified form of the enzyme, since it co-migrated with a form modified in vitro and had a similarly increased apparent Km for phosphoenolpyruvate. To rule out the possibility of this being a phosphorylated form of pyruvate kinase, the enzyme was incubated with a phosphoprotein phosphatase and then phosphorylated with cAMP-dependent protein kinase. The enzyme was not phosphorylated, like pyruvate kinase modified with subtilisin or calcium-activated protease. There is some evidence that a proteolytically modified pyruvate kinase exists in vivo. This enzyme form has not previously been demonstrated in cell sap, prior to exposure to proteolytic enzymes. The relative amounts of the three forms were determined in livers from starved rats and rats fed on a normal or a carbohydrate-rich diet.

  • 40.
    Nilsson Ekdahl, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The effect of fructose-2,6-bisphosphate and AMP on unphosphorylated and phosphorylated fructose-1,6-bisphosphatase from rat liver1984In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 167, no 2, p. 203-209Article in journal (Refereed)
    Abstract [en]

    Rat liver fructose-1,6-bisphosphatase was partially phosphorylated in vitro and separated into unphosphorylated and fully phosphorylated enzyme. The effects of fructose 2,6-bisphosphate and AMP on these two enzyme forms were examined. Unphosphorylated fructose-1,6-bisphosphatase was more easily inhibited by both effectors. Fructose 2,6-bisphosphate affected both K0.5 and Vmax, while the main effect of AMP was to lower Vmax. Fructose 2,6-bisphosphate and AMP together acted synergistically to decrease the activity of fructose-1,6-bisphosphatase, and since unphosphorylated and phosphorylated enzyme forms are affected differently, this might be a way to amplify the effect of phosphorylation.

  • 41.
    Prasthofer, T
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, B
    Ekman, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Owens, R
    Hook, M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Johansson, Staffan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Protein kinase C phosphorylates two of the four known syndecan cytoplasmic domains in vitro1995In: Biochemistry and Molecular Biology International, ISSN 1039-9712, Vol. 36, no 4, p. 793-802Article in journal (Refereed)
    Abstract [en]

    The transmembrane heparan sulfate proteoglycans of the syndecan family are implicated to participate in several cellular reactions which are dependent on protein kinase C. We have used an in vitro assay to assess whether any of the Peptides corresponding to the complete cytoplasmic domains of rat syndecans 1 through 4 were used as substrates for the enzyme. The syndecan-2 (fibroglycan) and syndecan-3 (N-syndecan) peptides were both found to be phosphorylated by protein kinase C with Kms of 15 +/- 3 microM and 85 +/- 25 microM, respectively, while the syndecan-1 and -4 peptides were not phosphorylated under the conditions used. The sites of in vitro phosphorylation for syndecans-2 and -3 were localized to ser-197 and ser-339, respectively. Thus, among 13 available sites (serines and threonines) in the four peptides, two were selectively modified by the enzyme. The specificity and the kinetics of the reactions indicate that the cytoplasmic domains of syndecan-2 and -3 are likely to be physiological substrates for protein kinase C.

  • 42.
    Rasmussen, I
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Upper Abdominal Surgery.
    Lebel, L
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Arvidsson, Dag
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Upper Abdominal Surgery.
    Haglund, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Upper Abdominal Surgery.
    Laurent, T C
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Gerdin, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Plastic Surgery.
    Hepatic extraction of hyaluronic acid in porcine peritonitis1995In: European Surgical Research, ISSN 0014-312X, E-ISSN 1421-9921, Vol. 27, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    The hepatic extraction of hyaluronic acid (HA) was studied in porcine fecal peritonitis in two groups of animals given various amounts of volume substitution. There was a progressive decrease in hepatic blood flow (QH) and a corresponding increase in the plasma concentration of HA in arterial blood over a 5-hour observation period, less pronounced in animals given more volume substitution. While hepatic clearance of HA decreased, the extraction ratio over the liver was not altered. The extracted amount of HA, which at steady state reflects the turnover of HA, was also unchanged. There was a significant correlation between QH and arterial HA concentration (r = 0.57; p < 0.05). The data suggest that the arterial HA concentration in sepsis reflects QH rather than an altered ability of the liver to eliminate HA.

  • 43.
    Razi, Nahid
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Kreuger, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lay, L
    Russo, G
    Panza, L
    Lindahl, Birgitta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Geriatrics.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Identification of O-sulphate substituents on D-glucuronic acid units in heparin-related glycosaminoglycans using novel synthetic disaccharide standards.1995In: Glycobiology, ISSN 0959-6658, E-ISSN 1460-2423, Vol. 5, no 8, p. 807-811Article in journal (Refereed)
    Abstract [en]

    The two disaccharides, methyl 4-O-(2-O-sulpho-beta-D-glucopyranosyl-uronic acid)-2-deoxy-2-amino-alpha-D-glucopyranoside and methyl 4-O-(3-O-sulpho-beta-D-glucopyranosyluronic acid)-2-deoxy-2-amino-alpha-D-glucopyranoside, were prepared by de novo synthesis, and converted to the corresponding 2,5-anhydro-D-[1-3H]mannitol derivatives by deamination with nitrous acid followed by reduction with NaB3H4. The resultant labelled products were used as standards in the identification, by anion-exchange high-performance liquid chromatography (HPLC), of disaccharides generated by HNO2/NaB3H4 treatment of heparan sulphate isolated from human brain. The two standards, containing 2-O- and 3-O-sulphated glucuronic acid, respectively, were clearly separated by the HPLC procedure. Comparison with the deamination products derived from heparan sulphate showed that the mono-O-sulphated disaccharide species containing a sulphated glucuronic acid unit co-eluted with the 2-O-sulphated standard. The corresponding component isolated from other heparan sulphate preparations, or from heparin, also eluted at the same position. No disaccharide derived from heparin or heparan sulphate appeared at the elution position of the 3-O-sulphated standard. It is concluded that D-glucuronic acid units in heparin-related glycosaminoglycans may be sulphated at C2, whereas no evidence has been found for sulphation at C3. By contrast, analysis of mono-O-sulphated disaccharides derived from a chemically sulphated, bacterial capsular polysaccharide (generated by Escherichia coli K5) clearly demonstrated the occurrence of O-sulphate groups at C-3 of D-glucuronic acid units.

  • 44.
    Reuterdahl, C
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Sundberg, Christian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Funa, K
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Gerdin, B
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Tissue localization of beta receptors for platelet-derived growth factor and platelet-derived growth factor B chain during wound repair in humans1993In: Journal of Clinical Investigation, ISSN 0021-9738, E-ISSN 1558-8238, Vol. 91, no 5, p. 2065-2075Article in journal (Refereed)
    Abstract [en]

    The expression and localization of PDGF beta receptors and PDGF-AB/BB in human healing wounds was evaluated by immunohistochemical techniques and in situ hybridization. Expression of PDGF beta receptor protein and PDGF-AB/BB were analyzed in wound margin biopsies using the PDGFR-B2 and PDGF 007 antibodies. PDGF beta receptor expression was minor in normal skin. An increased expression of PDGF beta receptor protein was prominent in vessels in the proliferating tissue zone in wounds as early as 1 d after surgery and was apparent < or = 4 wk after surgery. There was also a concordant increase in PDGF beta receptor mRNA detected by in situ hybridization. PDGF-AB/BB was present in healing wounds as well as in normal skin. In normal skin, expression of PDGF-AB/BB was confined to peripheral nerve fibers and to solitary cells of the epidermis and of the superficial dermis. In wounds, infiltrating mononuclear cells also stained for PDGF-AB/BB. To identify cell types expressing PDGF AB/BB and PDGF beta receptors, respectively, we performed double immunofluorescence stainings. PDGF beta receptors were expressed by vascular smooth muscle cells and cells in capillary walls; the receptor protein could not be detected in neurofilament containing structures, T lymphocytes, or CD68 expressing macrophages. PDGF-AB/BB colocalized with neurofilaments, it was present in Langerhans cells of the epidermis and in HLA-DR positive cells located in the epidermal/dermal junction area. Of the macrophages infiltrating the wound, 43 +/- 18% stained positively for PDGF AB/BB. Since PDGF-AB/BB and PDGF beta receptors are expressed in the healing wound, two essential prerequisites for a role of PDGF in wound healing are fulfilled.

  • 45.
    Salmivirta, Markku
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lidholt, Kerstin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindahl, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Heparan sulfate: a piece of information.1996In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 10, no 11, p. 1270-1279Article in journal (Refereed)
    Abstract [en]

    The sulfated glycosaminoglycans, heparan sulfate and heparin, are increasingly implicated in cell-biological processes such as cytokine action, cell adhesion, and regulation of enzymic catalysis. These activities generally depend on interactions of the polysaccharides with proteins, mediated by distinct saccharide sequences, and expressed at various levels of specificity, selectivity, and molecular organization. The formation of heparin/heparan sulfate in the cell requires an elaborate biosynthetic machinery, that is conceived in terms of a novel model of glycosaminoglycan assembly and processive modification. Recent advances in the identification and molecular analysis of the enzymes and other proteins involved in the biosynthesis provide novel tools to study the regulation of the process, presently poorly understood, at the subcellular and cellular levels. The potential medical importance of heparin-related compounds is likely to promote the biotechnological exploitation of components of the biosynthetic machinery.

  • 46.
    Sundberg, Christian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Branting, M
    Gerdin, B
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Tumor cell and connective tissue cell interactions in human colorectal adenocarcinoma: Transfer of platelet-derived growth factor-AB/BB to stromal cells1997In: American Journal of Pathology, ISSN 0002-9440, E-ISSN 1525-2191, Vol. 151, no 2, p. 479-492Article in journal (Refereed)
    Abstract [en]

    Mechanisms underlying stimulation of platelet-derived growth factor (PDGF) beta-receptors expressed on connective tissue cells in human colorectal adenocarcinoma were investigated in this study. PDGF-AB/BB, but not PDGF receptors, was expressed by tumor cells in situ, as well as in tumor cell isolates of low passage from human colorectal adenocarcinoma. In an experimental co-culture system, conditioned medium from tumor cells only marginally activated PDGF beta-receptors expressed on fibroblasts. In contrast, co-culturing of the two cell types led to a marked PDGF beta-receptor activation. Functional PDGF-AB/BB was found to be associated with heparinase-I-sensitive components on the tumor cell surface. PDGF-AB/BB, isolated from heparinase-I-sensitive cell surface components, induced a marked activation of PDGF beta-receptors. Furthermore, co-culturing tumor cells together with fibroblasts led to a sustained activation of PDGF beta-receptors expressed on fibroblasts. Double immunofluorescence staining of tissue sections from human colorectal adenocarcinoma, combined with computer-aided image analysis, revealed that nonproliferating tumor cells were the predominant cellular source of PDGF-AB/BB in the tumor stroma. In addition, PDGF-AB/BB-expressing tumor cells were found juxtapositioned to microvascular cells expressing activated PDGF beta-receptors. Confocal microscopy revealed a cytoplasmic and cell-membrane-associated expression of PDGF-AB/BB in tumor cells situated in the stroma. In contrast, epithelial cells situated in normal or tumorous acinar structures revealed only a cell-membrane-associated PDGF-AB/BB expression. The is vitro and in situ results demonstrate that tumor cells not only facilitate but also have the ability to modulate connective tissue cell responsiveness to PDGF-AB/BB in a paracrine fashion, through direct cell-cell interactions in human colorectal adenocarcinoma.

  • 47.
    Sundberg, Christian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ljungström, M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Lindmark, G
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Gerdin, B
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Microvascular pericytes express platelet-derived growth factor-beta receptors in human healing wounds and colorectal adenocarcinoma1993In: American Journal of Pathology, ISSN 0002-9440, E-ISSN 1525-2191, Vol. 143, no 5, p. 1377-1388Article in journal (Refereed)
    Abstract [en]

    The expression of platelet-derived growth factor- beta (PDGF-beta) receptors in the microvasculature of human healing wounds and colorectal adenocarcinoma was investigated. Frozen sections were subjected to double immunofluorescence staining using monoclonal antibodies (MAbs) specific for pericytes (MAb 225.28 recognizing the high-molecular weight-melanoma-associated antigen, expressed by activated pericytes during angiogenesis), endothelial cells (MAb PAL-E), laminin, as well as PDGF-beta receptors (MAb PDGFR-B2) and its ligand PDGF-B chain (MAb PDGF 007). Stained sections were analyzed by computer-aided imaging processing that allowed for a numerical quantification of the degree of colocalization of the investigated antigens. An apparent background colocalization, varying between 23 and 35%, between markers for cells not expected to co-localize was recorded. This background could be due to limitations of camera resolution, to out-of-focus fluorescence, and to interdigitations of the investigated structures. In all six tumor specimens, co-localization of PDGF-beta receptors and PAL-E was not different from the background co-localization, whereas that of PDGF-beta receptors and high-molecular weight-melanoma-associated antigen was significantly higher with mean values between 57 and 71%. Qualitatively, the same pattern was obtained in the two investigated healing wounds. PDGF-B chain did not co-localize with either PAL-E or high-molecular weight-melanoma-associated antigen, but PDGF-B chain-expressing cells were, however, frequently found juxtaposed to the microvasculature. The expression of PDGF-beta receptors on pericytes in activated microvessels and the presence of PDGF-B chain-expressing cells in close proximity to the microvasculature of healing wounds and colorectal adenocarcinoma is compatible with a role for PDGF in the physiology of the microvasculature in these conditions.

  • 48.
    Sundberg, Christian
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Stimulation of beta1 integrins on fibroblasts induces PDGF independent tyrosine phosphorylation of PDGF beta-receptors1996In: Journal of Cell Biology, ISSN 0021-9525, E-ISSN 1540-8140, Vol. 132, no 4, p. 741-752Article in journal (Refereed)
    Abstract [en]