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  • 1.
    Ahlgren, Joakim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Waldebäck, Monica
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Rydin, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR2005In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 39, no 3, p. 867-872Article in journal (Refereed)
    Abstract [en]

    Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.

  • 2.
    Bazoti, F N
    et al.
    GAIA Research Center, The Goulandris Natural History Museum, Greece.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Tsarbopoulos, A
    GAIA Research Center, The Goulandris Natural History Museum and Pharmacy Department, Laboratory of Pharmaceutical Instrumental Analysis, University of Patras, Greece.
    Screening potential inhibitors against Alzheimer's amyloidosis using electrospray ionization mass spectrometry2008In: Planta Medica, ISSN 0032-0943, E-ISSN 1439-0221, Vol. 74, no 9, p. 920-920Article in journal (Other academic)
  • 3. Bazoti, Fotini N.
    et al.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Markides, Karin E.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Tsarbopoulos, Anthony
    Noncovalent interaction between amyloid-b-peptide (1-40) and oleuropein studied by electrospray ionization mass spectrometry.2006In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 17, no 4, p. 568-575Article in journal (Refereed)
    Abstract [en]

    Beta amyloid peptide (A beta) is the major proteinaceous component of senile plaques formed in Alzheimer's disease (AD) brain. The aggregation of A beta is associated with neurodegeneration, loss of cognitive ability, and premature death. It has been suggested that oxidative stress and generation of free radical species have implications in the fibrillation of A beta and its subsequent neurotoxicity. For this reason, it is proposed that antioxidants may offer a protective or therapeutic alternative against amyloidosis. This study is the first report of the formation of the noncovalent complex between A beta or its oxidized form and the natural derived antioxidant oleuropein (OE) by electrospray ionization mass spectrometry (ESI MS). ESI MS allowed the real time monitoring of the complex formation between A beta, OE, and variants thereof. Several experimental conditions, such as elevated orifice potential, low pH values, presence of organic modifier, and ligand concentration were examined, to assess the specificity and the stability of the formed noncovalent complexes.

  • 4.
    Bazoti, Fotini N.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Tsarbopoulos, Anthony
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Localization of the Noncovalent Binding Site Between Amyloid-B-Peptide and Oleuropein Using Electrospray Ionization FT-ICR Mass Spectrometry2008In: J. Am. Soc. Mass. Spectrom., no 19, p. 1078-1085Article in journal (Refereed)
  • 5.
    Bazoti, Fotini N
    et al.
    GAIA Research Center, The Goulandris Natural History Museum and Department of Pharmacy, Laboratory of Instrumental Analysis, University of Patras, Greece.
    Tsarbopoulos, Anthony
    GAIA Research Center, The Goulandris Natural History Museum and Department of Pharmacy, Laboratory of Instrumental Analysis, University of Patras, Greece.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Study of the non-covalent interaction between amyloid-beta-peptide and melatonin using electrospray ionization mass spectrometry2005In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 40, no 2, p. 182-192Article in journal (Refereed)
    Abstract [en]

    Oxidative stress and unregulated immune response are believed to play a key role in the processes inherent to Alzheimer's disease (AD). The fact that free radicals can result in neurodegeneration suggests that actions against reactive oxygen species may be beneficial in treating and preventing AD. In the light of the suggested link between oxidative stress and AD, it is proposed that antioxidants and, even more, endogenous antioxidants may offer a therapeutic regime for protection against the risk of this disease. For this reason, the formation of non-covalent complexes between amyloid-beta-peptide (A beta) or its oxidized forms and melatonin was studied by quadrupole and Fourier transform ion cyclotron resonance electrospray ionization mass spectrometry. The stability of the non-covalent complex was examined under several experimental conditions, such as orifice voltage, pH, presence of organic modifier, concentration and time. Two different digestion protocols combined with mass spectrometric analysis of the resulting peptide fragments were employed in order to locate the binding site of melatonin in A beta.

  • 6.
    Bergström, Sara K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Dahlin, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Ramström, Margareta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Andersson, Marit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    A simplified multidimensional approach for analysis of complex biological samples: on-line LC-CE-MS2006In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 131, no 7, p. 791-798Article in journal (Refereed)
    Abstract [en]

    Information on protein expression, disease biomarkers or surrogate markers and genetic disorders can nowadays be achieved from analysis of complex biological samples by liquid separation coupled to mass spectrometric (MS) detection. This paper describes fast multidimensional separation by on-line liquid chromatography (LC) and capillary electrophoresis (CE), followed by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) MS detection. This detector provides ultrahigh resolution of the detected ions, mass accuracy at the ppm-level and high sensitivity. Most of the challenge of this system lies in the development of a new interface for the on-line coupling of LC to CE. The interface developed in poly(dimethylsiloxane) provides a RSD for injection repeatability of <3.5% and surface control for unspecific binding by deactivation with a cationic polymer, PolyE-323. We have evaluated the interface, as well as the overall system, with respect to robustness and deconvolution ability. Sequence coverage for bovine serum albumin (BSA) of 93% showed a high recovery of sample in the different transfer steps through the system. The detection limit for identification is 277 ng mL−1 (or 280 nM) on average for peptides. In the future, we expect LC-CE-MS to be a novel strategy for elucidating the chemistry of biological matrices.

  • 7.
    Bökman, C Fredrik
    et al.
    Clinical Chemistry Laboratory, Falun Central Hospital.
    Bylund, Dan
    Department of Natural Sciences, Mid Sweden University.
    Markides, Karin E
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets.2006In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 17, no 3, p. 318-24Article in journal (Refereed)
    Abstract [en]

    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.

  • 8.
    Galanakis, Petros A.
    et al.
    Department of Pharmacy, University of Patras, Panepistimioupoli, Greece.
    Bazoti, Fotini N.
    Department of Pharmacy, University of Patras, Panepistimioupoli and GAIA Research Center, Bioanalytical Department, Greece. .
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Spyroulias, Georgios A.
    Department of Pharmacy, University of Patras, Panepistimioupoli, Greece.
    Tsarbopoulos, Anthony
    Department of Pharmacy, University of Patras, Panepistimioupoli and GAIA Research Center, Bioanalytical Department, Greece..
    Study of the Interaction Between the Amyloid Beta Peptide (1-40) and Antioxidant Compounds by Nuclear Magnetic Resonance Spectroscopy2011In: Biopolymers, ISSN 0006-3525, E-ISSN 1097-0282, Vol. 96, no 3, p. 316-327Article in journal (Refereed)
    Abstract [en]

    Amyloid beta peptide (Aβ) aggregation leads to the senile plaque formation, a process that is strongly influenced by oxidative stress and is considered as the molecular basis of various neurodegenerative diseases, such as Alzheimer's Disease (AD). Endogenous antioxidants or dietary derived compounds may down-regulate this process. In this study, the interaction of two antioxidants, oleuropein (OE) and melatonin (M) with Aβ, is monitored through NMR spectroscopy and Mass Spectrometry. The concerted application of these two analytical techniques provides new experimental evidence and residue-specific insights into the interacting Aβ peptide amino acids that are implicated in this process. Both antioxidant compounds interact in a similar way with the peptide and cause chemical shift variations. The most pronounced resonance changes have been observed for the (1)H-(15)N signals of N-terminal region and Leu(17)-Phe(20) residues, as monitored by NMR titration studies.

  • 9.
    Hardenborg, Emilia
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Zuberovic, Aida
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Ullsten, Sara
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Söderberg, Lennart
    Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Heldin, Eva
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Novel polyamine coating providing non-covalent deactivation and reversed electroosmotic flow of fused-silica capillaries for capillary electrophoresis2003In: J. of Chromatography A, no 1003, p. 217-221Article in journal (Refereed)
  • 10.
    Isaac, Giorgis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Bylund, Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Månsson, Jan-Eric
    Institute of Clinical Neuroscience, Sahlgrenska University Hospital, Göteborg University, Sweden.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Analysis of phosphatidylcholine and sphingomyelin molecular species from brain extracts using capillary liquid chromatography electrospray ionization mass spectrometry2003In: Journal of Neuroscience Methods, ISSN 0165-0270, E-ISSN 1872-678X, Vol. 128, no 1-2, p. 111-119Article in journal (Refereed)
    Abstract [en]

    One feature of complex lipids is that many subtypes of these molecules exist as a diverse mixture in a biological sample. Qualitative and quantitative analysis of these closely related molecules require sensitive and specific analytical methods to detect intact phospholipids (PL) and sphingomyelin (SM) species and to differentiate between them. Conventional analytical methods require laborious procedures including separation by column, argentation thin-layer chromatography or liquid chromatography (LC) after pre- or post-column derivatization. In the present work, a method based on reversed phase capillary LC coupled on-line to electrospray ionization mass spectrometry (LC/ESI/MS) has been developed to gather tools for lipidomic studies, i.e. the profiling of complex mixtures of lipids in small amounts of various cells and tissues. The LC/MS system used consisted of an LC pump in an isocratic elution, a reversed phase capillary column and a single quadrupole mass spectrometer operated in the positive ion mode. A successful separation of phosphatidylcholine (PC) and SM molecular species was obtained with a minimum detectable quantity (MDQ) in the low fmol range injected on column. The method was applied to human brain extracts. Furthermore, the extraction efficiencies of the traditional Folch method and pressurized fluid extraction (PFE) were compared using the human brain. It was found that the intensity of the PC and SM molecular species extracted by PFE is two times that of Folch.

  • 11. Jastrebova, J
    et al.
    Nyholm, L
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Markides, K
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Bergqvist, Y
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    On-Line Deoxygenation for Reductive Electrochemical Detection of Artemisinin and Dihydroartemisinin in Liquid Chromatography1998In: The Analyst, ISSN 0003-2654, Vol. 123, p. 313-Article in journal (Refereed)
  • 12.
    Lavén, Martin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Itsenko, Oleksiy
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Biochemistry and Organic Chemistry.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Determination of metabolic stability of positron emission tomography tracers by LC-MS/MS: An example in WAY-100635 and two analogues2006In: J. of Pharmaceutical and Biomedical Analysis, no 40, p. 943-951Article in journal (Refereed)
  • 13.
    Lavén, Martin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Velikyan, Irina
    Djodjic, Majda
    Ljung, Jenny
    Berglund, Oskar
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Långström, Bengt
    Wallenborg, Susanne
    Imaging of peptide adsorption to microfluidic channels in a plastic compact disc using a positron emitting radionuclide2005In: Lab Chip, no 5, p. 756-763Article in journal (Refereed)
    Abstract [en]

    A method for studying peptide-surface interactions within microfluidic channels by radionuclide imaging is described. With the high surface area-to-volume ratio of channels in miniaturised devices, combined with low amunts of analyte, non-specific peptide adsorption is a critical issue. The objective of the study was therefore to develop a method capable of direct detection of adsorbed peptide within microfluidic channels. A micro-device consisting of channels moulded in a plastic compact disc was chosen for the study, together with two selected peptides of different lengths and isolelectric point (pI) values. A bifunctional chelator, DOTA, was attached to the peptide by conjugation and labelled with the short-lived positron emitting radionuclide 68Ga. Quantitative images of radiotracer distribution within the microfluidic channels were obtained using a PhosphorImager system. The power of the method was demonstrated by the ability to clearly measure changes in adsorption when varying a number of parameters that typically affect peptide adsorption. These included surface modifications, analyte concentration, pH, and ionic strength. Additionally, two quantification methods were developed and compared. Radionuclide imaging also permitted visualisation of adsorption and release processes in microchannel chromatographic columns. The results suggest that radionuclide imaging is a suitable tool not only for the study of peptide adsorption to the microchannels presented in this study but also as a versatile tool to measure peptide-surface interactions in a wide variety of miniaturised structures and devices.

  • 14.
    Nilsson, S L
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Andersson, C
    Astra Zeneca R&D Lund.
    Sjöberg, P J R
    Gyros AB, Uppsala Science Park.
    Bylund, D
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Petersson, P
    Astra Zeneca R&D Lund.
    Jörntén-Karlsson, M
    Astra Zeneca R&D Lund.
    Markides, K E
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Phosphate buffers in capillary electrophoresis/mass spectrometry using atmospheric pressure photoionization and electrospray ionization.2003In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 17, no 20, p. 2267-72Article in journal (Refereed)
    Abstract [en]

    Capillary electrophoresis (CE) has been combined with atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) for mass spectrometric (MS) detection. Separation conditions using potassium phosphate buffer and ammonium formate buffer have been compared for analysis of eleven pharmaceutical bases. The results showed improvements in separation efficiency and peak symmetry when phosphate buffer was used. The low flow in CE may enable utilization of these advances with MS detection. Compared with ESI, the APPI technique provided a cluster-free background. The enhanced signal-to-noise ratio in the total ion current (TIC) and the reduced spectral background indicated that the APPI process is less affected by non-volatile salts in the CE buffers. This results in a wider range of choice of CE buffers in CE/MS analysis when APPI is the ionization method.

  • 15.
    Ramström, Margareta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Hagman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Tsybin, Youri O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Håkansson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Salehi, Albert
    Department of Pharmacology, Institute of Physiological Sciences, Lund University.
    Lundquist, Ingmar
    Department of Pharmacology, Institute of Physiological Sciences, Lund University.
    Håkanson, Rolf
    Department of Pharmacology, Institute of Physiological Sciences, Lund University.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    A novel mass spectrometric approach to the analysis of hormonal peptides in extracts of mouse pancreatic islets2003In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 270, no 15, p. 3146-3152Article in journal (Refereed)
    Abstract [en]

    Liquid chromatography mass spectrometry (LC-MS) is a valuable tool in the analysis of proteins and peptides. The combination of LC-MS with different fragmentation methods provides sequence information on components in complex mixtures. In this work, on-line packed capillary LC electrospray ionization Fourier transform ion cyclotron resonance MS was combined with two complementary fragmentation techniques, i.e. nozzle-skimmer fragmentation and electron capture dissociation, for the determination of hormonal peptides in an acid ethanol extract of mouse pancreatic islets. The most abundant peptides, those derived from proinsulin and proglucagon, were identified by their masses and additional sequence-tag information established their identities. Interestingly, the experiments demonstrated the presence of truncated C-peptides, des-(25-29)-C-peptide and des-(27-31)-C-peptide. These novel findings clearly illustrate the potential usefulness of the described technique for on-line sequencing and characterization of peptides in tissue extracts.

  • 16.
    Ramström, Margareta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Palmblad, Magnus
    Jonfysik. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Markides, Karin E
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Håkansson, Per
    Jonfysik. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Protein identification in cerebrospinal fluid using packed capillary liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry2003In: Proteomics, Vol. 3, no 2, p. 184-190Article in journal (Refereed)
    Abstract [en]

    The identification and characterization of proteins in complex biological samples such as body fluids, require powerful and reliable tools. Mass spectrometry is today one of the most important methods in such research. This paper reports on the results from the first experiment where a tryptic digest of cerebrospinal fluid was analyzed applying reversed phase liquid chromatography coupled on-line to a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer. In total, 70 204 peaks were detected, which originated from 16 296 isotopic clusters corresponding to 6551 unique peptide masses. From these masses, 39 proteins were identified in the sample. The amount of sample required for one experiment corresponds to 32 μL of cerebrospinal fluid.

  • 17.
    Santos-Neto, Alvaro J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Sjöberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Lancas, Fernando M.
    Capillary Column Switching Restricted-Access Media-Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry System for Simultaneous and Direct Analysis of Drugs in Biofluids2007In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, no 16, p. 6359-6367Article in journal (Refereed)
    Abstract [en]

    Capillary online restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry (RAM-LC-ESI-MS/MS) for direct analysis of drugs and metabolites spiked in biological fluids was developed. Using a column switching setup it was possible to perform effective sample preparation and analysis of raw biological fluids (plasma and urine) without matrix effects in the electrospray mass spectrometric detection step. The peak focusing efficiency of the extraction column was more effective in backflush compared to foreflush mode. The system was able to concentrate diminished samples of polar drugs and their metabolites reaching quantifiable results as low as 1 ng/mL utilizing a sample volume of only 333 nL of biofluids. New column hardware was developed to circumvent clogging problems experienced with plasma injections. The glass fiber filter frit, which is commonly used, was replaced with a short piece of 20 μm i.d. fused silica capillary. The extraction columns were able to handle up to 60 injections and showed a high loading capacity, making the saturation of the MS detector the limiting factor on the linear dynamic range. The simultaneous separation and detection of 10 drugs and metabolites was obtained in 8 min of analysis, including the online sample preparation and enrichment step.

  • 18.
    Thorslund, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Bergström, S
    Johanesson, N
    Pettersson, A
    Liljegren, G
    Magnusson, K
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hallberg, M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Klett, Oliver
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Bergquist,, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Nyberg, F
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Nikolajeff, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Essential components in an integrated platform for on-site screening of anabolic androgenic steroids in biological samples2004In: Micro Total Analysis Systems 2004: Vol 1 / [ed] Laurell T; Nilsson J; Jensen K; Harrison DJ; Kutter JP, 2004Conference paper (Refereed)
    Abstract [en]

    In this abstract new results concerning the introduction of a biological sample into a mu TAS, the avoidance of unspecific absorbance in the mu TAS and the interfacing to off-chip detection (e.g. Mass spectrometry, MS) for verification are presented.

  • 19.
    Turner, Charlotta
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Quan, Can
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Turner, Pernilla
    Nordberg Karlsson, Eva
    Waldebäck, Monica
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Pressurized fluid extraction and biocatalysis - applications on health-beneficial compounds in plants2006In: 8th International Symposium on supercritical Fluids, Kyoto, Japan, 2006Conference paper (Other scientific)
  • 20.
    Turner, Charlotta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Turner, Pernilla
    Department of Biotechnology, Lund University.
    Jacobson, Gunilla
    Department of Chemistry, Stanford university.
    Almgren, Knut
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Waldebäck, Monica
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sjöberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Karlsson, Eva Nordberg
    Department of Biotechnology, Lund University.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Subcritical water extraction and beta-glucosidase-catalyzed hydrolysis of quercetin glycosides in onion waste2006In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 8, no 11, p. 949-959Article in journal (Refereed)
    Abstract [en]

    Onion waste is a renewable raw material, rich in different molecular species of the antioxidant quercetin. To utilize this resource, an environmentally sustainable procedure has been developed, using pressurized hot water to extract the quercetin species, followed by biocatalytic conversion of the quercetin glycosides to quercetin and carbohydrates. Two different recombinantly expressed thermostable beta-glucosidases, Thermotoga neapolitana beta-glucosidase A and B, were utilized as catalysts. These enzymes maintain activity at temperatures around 90 degrees C, and are therefore ideal to use in combination with hot water extraction. Our results, based on experimental design, showed that they converted quercetin glycosides to active quercetin in less than 10 min reaction time in water at 90 degrees C, pH 5.0. Experimental design showed that the optimal extraction conditions included three 5 min extraction cycles with water at 120 degrees C and 50 bars, giving a total extraction time of 15 min. Several different types of quercetin and isorhamnetin glycosides as well as kaempferol were detected in onion waste using LC-MS/MS analysis. After converting the different glycosidic compounds to their respective aglycones, the quercetin content was 10 to 50 mg g(-1) dry weight of onion waste (RSD 8%). In summary, our research demonstrates that subcritical water extraction followed by beta-glucosidase-catalyzed hydrolysis is a rapid method to determine the content of quercetin and isorhamnetin in onion samples, and is environmentally sustainable as it only uses water as solvent and enzymes as catalysts.

  • 21.
    Turner, Charlotta
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Turner, Pernilla
    Jacobson, Gunilla
    Nordberg Karlsson, Eva
    Waldebäck, Monica
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Pressurized Hot Water Extraction and Enzyme-Catalyzed Conversion of Polyphenolic Glycosides in Onion Waste2005In: 10th European meeting on Superciritical Fluids, Colmar, France, 2005Conference paper (Other scientific)
  • 22.
    Waldeback, Monica
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Rydin, Emil
    Department of Evolutionary Biology. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Use of accelerated solvent extraction for determination of ecological important phosphorus in lake sediments1998In: INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY, ISSN 0306-7319, Vol. 72, no 4, p. 257-266Article in journal (Refereed)
    Abstract [en]

    Phosphorus has been identified as one of the most important elements in eutrophication of lakes. and the bulk of phosphorus compounds stored in lake sediment contribute to a large extent to this process. It is therefore of great interest to get an adequa

  • 23.
    Örnskov, Eivor
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Ullsten, Sara
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Söderberg, Lennart
    Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Folestad, Staffan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Method for immobilization of liposomes in capillary electrophoresis by electrostatic interaction with derivatized agarose2002In: Electrophoresis, ISSN 3381-3384, Vol. 23, p. 3381-3384Article in journal (Refereed)
    Abstract [en]

    A novel procedure for immobilization of liposomes inside fused-silica capillaries is

    demonstrated. First, the inner wall of the capillaries was coated with a positively

    charged polymer, composed of derivatized agarose. Subsequently, negatively charged

    liposomes were immobilized by electrostatic interaction on the polymer coating. The

    developed liposome coated capillaries were used as a nanoseparation tool for studying

    interactions between small drug compounds and liposomes. Part of this work was

    presented at the 15th International Symposium on Microscale Separations and Analysis,

    HPCE 2002, Stockholm, Sweden, April 2002.

1 - 23 of 23
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