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  • 201.
    Timmusk, Salme
    et al.
    Department of forest Mycology and Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU).
    Paalme, Viiu
    Department of Gene Technology, Tallinn University, Estonia.
    Pavlicek, Tomas
    Institute of Evolution, University of Haifa, Israel.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Vengala, Ameraswar
    Department of forest Mycology and Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU).
    Danilas, Triin
    Institute of Forest and Rural Engineering, Estonian University of Life Sciences, Estonia.
    Nevo, Eviatar
    Bacterial Distribution in the Rhizosphere of Wild Barley under Contrasting Microclimates2011In: PLoS ONE, ISSN 1932-6203, Vol. 6, no 3, p. e17968-Article in journal (Refereed)
    Abstract [en]

    Background:All plants in nature harbor a diverse community of rhizosphere bacteria which can affect the plant growth. Our samples are isolated from the rhizosphere of wild barley Hordeum spontaneum at the Evolution Canyon (‘EC’), Israel. The bacteria which have been living in close relationship with the plant root under the stressful conditions over millennia are likely to have developed strategies to alleviate plant stress.

    Methodology/Principal Findings:We studied distribution of culturable bacteria in the rhizosphere of H. spontaneum and characterized the bacterial 1-aminocyclopropane-1-carboxylate deaminase (ACCd) production, biofilm production, phosphorus solubilization and halophilic behavior. We have shown that the H. spontaneum rhizosphere at the stressful South Facing Slope (SFS) harbors significantly higher population of ACCd producing biofilm forming phosphorus solubilizing osmotic stress tolerant bacteria.

    Conclusions/Significance:The long-lived natural laboratory ‘EC’ facilitates the generation of theoretical testable and predictable models of biodiversity and genome evolution on the area of plant microbe interactions. It is likely that the bacteria isolated at the stressful SFS offer new opportunities for the biotechnological applications in our agro-ecological systems.

  • 202.
    Tolstoy, Päivi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Engman, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Paptchikhine, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Church, Tamara L
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Leung, Abby W-M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Iridium-Catalyzed Asymmetric Hydrogenation yielding Chiral Diarylmethines with Weakly Coordinating or Noncoordinating Substituents2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 25, p. 8855-8860Article in journal (Refereed)
    Abstract [en]

    Diarylimethine-containing stereocenters are present in pharmaceuticals   and natural products, making the synthetic methods that form these   chiral centers are important in industry. We have applied iridium   complexes with novel N,P-chelating ligands to the asymmetric  hydrogenation of trisubstituted olefins, forming diarylmethine chiral   centers in high conversions and excellent enantioselectivities (up to   99% ee) for a broad range of substrates. Our results support the hypothesis that steric hindrance in one specific area of the catalyst   is playing a key role in stereoselection, as the hydrogenation of   substrates differing little at the prochiral carbon occurred with high enantioselectivity. As a result, excellent stereodiscrimination was obtained even when the prochiral carbon bore, for example, phenyl and p-tolyl groups.

  • 203.
    Tsybin, Youri O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Ramström, Margareta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Witt, Matthias
    Baykut, Gökhan
    Håkansson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Peptide and Protein Characterization by High Rate Electron Capture Dissociation Fourier Transform Ion Cyclotron Resonance Mass Spectrometry2004In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 39, no 7, p. 719-729Article in journal (Refereed)
    Abstract [en]

    The analytical utility of the electron capture dissociation (ECD) technique, developed by McLafferty and co-workers, has substantially improved peptide and protein characterization using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The limitations of the first ECD implementations on commercial instruments were eliminated by the employment of low-energy electron-injection systems based on indirectly heated dispenser cathodes. In particular, the ECD rate and reliability were greatly increased, enabling the combination of ECD/FTICR-MS with on-line liquid separation techniques. Further technique development allowed the combination of two rapid fragmentation techniques, high-rate ECD and infrared multiphoton dissociation (IRMPD), in a single experimental configuration. Simultaneous and consecutive irradiations of trapped ions with electrons and photons extended the possibilities for ion activation/dissociation and led to improved peptide and protein characterization. The application of high-rate ECD/FTICR-MS has demonstrated its power and unique capabilities in top-down sequencing of peptides and proteins, including characterization of post-translational modifications, improved sequencing of peptides with multiple disulfide bridges and secondary fragmentation (w-ion formation). Analysis of peptide mixtures has been accomplished using high-rate ECD in bottom-up mass spectrometry based on mixture separation by liquid chromatography and capillary electrophoresis. This paper summarizes the current impact of high-rate ECD/FTICR-MS for top-down and bottom-up mass spectrometry of peptides and proteins.

  • 204.
    Turner, Charlotta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Analytisk kemi för en hållbar utveckling2009In: Livsmedel i fokus, ISSN 1652-912X, no 4, p. 40-40Article in journal (Other academic)
  • 205.
    Turner, Charlotta
    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.
    Overview of Modern Extraction Techniques for Food and Agricultural Samples2006In: Modern Extraction Techniques: Food and Agricultural Samples, American Chemical Society Press , 2006, p. Chapter 1-Chapter in book (Refereed)
  • 206.
    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.

  • 207.
    Ubhayasekera, Kumari
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Does Feed Containing Trans Fatty Acids Influence the Cholesterol and Oxycholesterols Levels in Chicken?2011In: Nutrition Focus Newsletter, Nutrition Society of Sri Lanka, no 3, p. 5-Article in journal (Other (popular science, discussion, etc.))
  • 208.
    Ubhayasekera, Sarojini J.K.A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Effects of Oxidized Lipids on Cholesterol and Cholesterol Oxidation in the Tissues of Chicken and Rabbit2008Conference paper (Refereed)
  • 209.
    Ubhayasekera, Sarojini J.K.A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Dutta, P. C.
    Department of Food Science, SLU, Sweden.
    Oxidation of Plant Sterols in the Industrial By-products of Edible Fats and Oils2010In: 101st AOCS Annual Meeting & Expo, Phoenix, Arizona, USA, May 16-19, 2010, AOCS Abstract, Urbana: AOCS Press , 2010, p. 17-Conference paper (Refereed)
  • 210.
    Ullsten, Sara
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Zuberovic, Aida
    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.
    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.
    Adsorbed Cationic Polymer Coatings for Enhanced Capillary Electrophoresis/Mass Spectrometry of Proteins2008In: Capillary Electrophoresis: Methods and Protocols, Humana Press, Totowa, NJ,USA , 2008, p. 631-646Chapter in book (Refereed)
  • 211.
    Ullsten, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Zuberovic, Aida
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Hardenborg, Emilia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    E. 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 polyamine coating for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry of proteins and peptides.2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 13, p. 2090-2099Article in journal (Refereed)
    Abstract [en]

    A procedure for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) of proteins is presented. The use of a newly presented capillary coating, PolyE-323, provided fast separations of typically a few minutes with high efficiency, good deactivation, and no bleeding into the mass spectrometer. Capillaries coated with PolyE-323 showed high stability over a range of pH 2-10, and tolerance towards methanol and acetonitrile, two modifiers commonly used in CE-ESI-MS. Due to the speed and simplicity of the coating procedure, the polymeric surface could, if necessary, easily be regenerated. This capability is especially valuable when working with samples of complex matrix, where a capillary surface cleaning step might be desired in order to eliminate possible memory effects. The potential of PolyE-323-coated capillaries in bioanalysis using CE-ESI-MS was demonstrated by analyzing peptides and proteins up to 66 kDa using time of flight (TOF)-MS. Due to the stable, anodal electroosmotic flow generated by the coating, the use of a sheathless ESI interface was enabled, demonstrated in peptide analysis with attomole sensitivity. The fast on-line CE-ESI-TOF system using PolyE-323-coated capillaries provided efficient separation and detection of a large number of peaks in a short time, exemplified by the analysis of a tryptic digest of bovine serum albumin (BSA). The capability of the developed capillary surface coating was demonstrated by the separation of human plasma and cerebrospinal fluid (CSF).

  • 212.
    Undin, Torgny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Samuelsson, Jörgen
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Törncrona, Anders
    AkzoNobel Pulp & Performance Chemicals AB, Bohus, Sweden.
    Fornstedt, Torgny
    Department of Engineering and Chemical Sciences, Karlstad University, Karlstad, Sweden.
    Evaluation of a combined linear–nonlinear approach for column characterization using modern alkaline-stable columns as model2013In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 36, no 11, p. 1753-1761Article in journal (Refereed)
    Abstract [en]

    This study investigates if deeper understanding is achieved when combining nonlinear and linear chromatographic column characterization methods. As test systems, two hybrid columns (Phenomenex Gemini-NX C18 and Kromasil Eternity C18) and one classic one (Kromasil-C18) were selected. The nonlinear methods were based on firm adsorption theory and involved determination of adsorption isotherms followed by calculations with a new numerical tool, adsorption energy distribution, on probe components at different pH values. The linear methods involved the hydrophobic subtraction model and selected probe components retention factors as a function of pH. The combined analysis indicated that both complementary and confirmative information can be achieved regarding the actual model systems.

  • 213.
    Vainikka, Kati
    et al.
    Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Finland.
    Reijmar, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Yohannes, Gebrenegus
    Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Finland.
    Samuelsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Jussila, Matti
    Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Finland.
    Riekkola, Marja-Liisa
    Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Finland.
    Polyethylene glycol-stabilized lipid disks as model membranes in interaction studies based on electrokinetic capillary chromatography and quartz crystal microbalance2011In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 414, no 1, p. 117-124Article in journal (Refereed)
    Abstract [en]

    Distearoylphosphatidylcholine (DSPC)/cholesterol/distearoylphosphatidylethanolamine (DSPE)-polyethylene glycol 5000 [PEG(5000)] lipid disks, mimicking biological membranes, were used as pseudostationary phase in partial filling electrokinetic capillary chromatography (EKC) to study interactions between pharmaceuticals and lipid disks. Capillaries were coated either noncovalently with a poly(1-vinylpyrrolidone)-based copolymer or covalently with polyacrylamide to mask the negative charges of the fused-silica capillary wall and to minimize interactions between positively charged pharmaceuticals and capillary wall. Although the noncovalent copolymer coating method was faster, better stability of the covalent polyacrylamide coating at physiological pH 7.4 made it more reliable in partial filling EKC studies. Migration times of pharmaceuticals were proportional to the amount of lipids in the pseudostationary phase, and partition coefficients were successfully determined. Because the capillary coatings almost totally suppressed the electroosmotic flow, it was not practical to use the EKC-based method for partition studies involving large molecules with low mobilities. Hence, the applicability of the biomembrane mimicking lipid disks for interactions studies with large molecules was verified by the quartz crystal microbalance technique. Biotinylated lipid disks were then immobilized on streptavidin-coated sensor chip surface, and interactions with a high-molecular-mass molecule, lysozyme, were studied. Cryo-transmission electron microscopy and asymmetrical flow field-flow fractionation were used to clarify the sizes of lipid disks used.

  • 214.
    Vallin, Örjan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindberg, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Danielsson, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Polishing of quartz by rapid etching in ammonium bifluoride2007In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 54, no 7, p. 1454-1462Article in journal (Refereed)
    Abstract [en]

    The etch rate and surface roughness of polished and lapped AT-cut quartz subjected to hot (90, 110, and 130 degrees C), concentrated (50, 65, 80 wt %) ammonium bi-fluoride have been investigated. Having used principal component analysis to verify experimental solidity and analyze data, we claim with confidence that this parameter space does not, as elsewhere stated, allow for a polishing effect or even a preserving setting. Etch rates were found to correlate well, and possibly logarithmically, with temperature except for the hottest etching applied to lapped material. Roughness as a function of temperature and concentration behaved well for the lapped material, but lacked systematic variation in the case of the polished material. At the lowest temperature, concentration had no effect on etch rate or roughness. Future efforts are targeted at temperatures and concentrations closer to the solubility limit.

  • 215.
    Varedian, Miranda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Langer, Vratislav
    Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    An unexpected triethylsilane-triggered rearrangement of thioaurones to thioflavonols under SPPS conditions2008In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 49, no 42, p. 6033-6035Article in journal (Refereed)
    Abstract [en]

    Thioaurones are converted to a mixture of thiaindenes and thioflavonols when exposed to reaction conditions employed in SPPS, that is, treatment with trifluoroacetic acid in the presence of triethylsilane.

  • 216.
    Végvári, Ákos
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Photochemistry and Molecular Science. Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wetterhall, Magnus
    Bergquist, Jonas
    Department of Chemistry. Department of Physical and Analytical Chemistry, Analytical Chemistry. Analytisk kemi.
    Technologies interfacing capillary electrophoresis to mass spectrometry2005In: Proteomics and Peptidomics – Technology Developments Driving Biology, Wilson & Wilson, Elsevier, Amsterdam , 2005, p. 447-484Chapter in book (Refereed)
  • 217.
    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

  • 218.
    Waldebäck, Monica
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Senorans, Javier
    Fridström, Anders
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Pressurized Fluid Extraction of Squalene from Olive Biomass2006In: Modern Extraction Techniques: Food and Agricultural Samples / [ed] Charlotta Turner, American Chemical Society (ACS), 2006Chapter in book (Other academic)
  • 219.
    Wetterhall, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Shevchenko, Ganna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Artemenko, Konstantin A
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sjödin, Marcus O.D.
    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 membrane and hydrophilic proteins simultaneously derived from the mouse brain using cloud-point extraction2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 400, no 9, p. 2827-2836Article in journal (Refereed)
    Abstract [en]

    In this study, a temperature-induced phase fractionation known as cloud-point extraction (CPE) with the non-ionic surfactant Triton X-114 was used to simultaneously extract, concentrate, and fractionate hydrophobic and hydrophilic proteins from mouse brain tissue. Two bottom-up proteomic techniques were used to comprehensively identify the extracted proteins. The first "shotgun"-based approach included tryptic digestion of the proteins followed by reversed-phase nanoliquid chromatography (RP-nanoLC) in combination with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). In the second approach, the extracted intact proteins were first separated by one-dimensional (1D) gel electrophoresis and then in-gel digested with trypsin and analyzed with nanoLC-MS/MS. In total, 1,825 proteins were unambiguously identified and the percentage of membrane proteins was 26% which is at the reported genome expression levels of 20-30%. The protein overlap between the two approaches was high. The majority (77%) of the identifications in the first approach was also found by the second method. The protein overlap between the CPE-extracted hydrophilic and hydrophobic fractions was rather small (16-23%) for both methods, which indicates a good phase separation. A quantitative evaluation of the CPE with iTRAQ labeling and nanoLC-ESI-MS/MS analysis gave iTRAQ ratios at the expected levels and an overall variation of the entire method at 17-31%. The results indicate very reproducible sample preparation and analysis methods that readily can be applied on large-scale sample sets.

  • 220.
    Wetterhall, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Zuberovic, Aida
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Hanrieder, Jörg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Assessment of the partitioning capacity of high abundant proteins in human cerebrospinal fluid using affinity and immunoaffinity subtraction spin columns.2010In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 878, no 19, p. 1519-1530Article in journal (Refereed)
    Abstract [en]

    The performance of three different affinity and immunoaffinity subtraction spin columns was investigated for the removal of the most abundant proteins in human cerebrospinal fluid (CSF). A pool of human CSF was processed with the spin columns and both the bound and flow through fractions were compared with each other and with intact CSF using 1D gel electrophoresis and nanoLC-MALDI-TOF/TOF-MS analysis. MASCOT MS/MS ionscores were compared before and after processing with the columns. The non-specific co-removal of proteins bound to the high abundant proteins, so called "sponge effect" was also examined for each spin column. The reproducibility of one of the spin columns, ProteomeLab IgY-12 proteome partitioning spin column, was further investigated by isobaric tags for relative and absolute quantification (iTRAQ) labeling and MS/MS analysis. Overall, 173 unique proteins were identified on a 95% MudPIT confidence scoring level. For all three spin columns, the number of proteins identified and their MASCOT scores were increased up to 10 times. The largest degree of non-specific protein removal was observed for a purely affinity based albumin removal column, where 28 other proteins also were present. The ProteomeLab IgY-12 proteome partitioning spin column showed very high reproducibility when combined with iTRAQ labeling and MS/MS analysis. The combined relative standard deviation (R.S.D.) for the high abundant protein removal, iTRAQ labeling and nanoLC-MALDI-TOF/TOF-MS analysis was less than 17.5%.

  • 221. Wolpher, Henriette
    et al.
    Sinha, Subrata
    Pan, Jingxi
    Johansson, Anh
    Lundqvist, Maria J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Persson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sun, Licheng
    Sundström, Villy
    Åkermark, Björn
    Polivka, Tomás
    Synthesis and Electron Transfer Studies of Ruthenium−Terpyridine-Based Dyads Attached to Nanostructured TiO22007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 3, p. 638-651Article in journal (Refereed)
    Abstract [en]

    A series of bis(terpyridine)Ru" complexes have been prepared, where one of the terpyridines is functionalized in the 4'-position by a phosphonic or carboxylic acid group for attachment to TiO2. The other is functionalized, also in the 4'-position, by a potential electron donor. In complexes 1a, 3a, and 4a,b, this donor is tyrosine or hydrogen-bonded tyrosine, while in 2a it is carotenoic amide. The synthesis and photophysical properties of the complexes are discussed. On irradiation with visible light, the formation of a long-lived charge-separated state was anticipated, via primary electron ejection into the TiO2, followed by secondary electron transfer from the donor to the photogenerated RuIII. However, such a charge-separated state could be observed with certainty only with complex 2a. To explain the result, quantum chemical calculations were performed on the different types of complexes.

  • 222. Xu, Yunhua
    et al.
    Eilers, Gerriet
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Borgström, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Pan, Jingxi
    Abrahamsson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Magnuson, Ann
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Polivka, Tomas
    Sun, Licheng
    Sundström, Villy
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Åkerman, Björn
    Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II2005In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, no 24, p. 7305-7314Article in journal (Refereed)
    Abstract [en]

    The structural rearrangements triggered by oxidation of the dinuclear Mn complex [Mn2(bpmp)(u-OAc)2]+ (bpmp = 2,6-bis[bis(2-pyridylmethyl)amino]methyl-4-methylphenol anion) in the presence of water have been studied by combinations of electrochemistry with IR spectroscopy and with electrospray ionization mass spectrometry (ESI-MS). The exchange of acetate bridges for water (D2O) derived ligands in different oxidation states could be monitored by mid-IR spectroscopy in CD3CN-D2O mixtures following the Vas(C-O) bands of bound acetate at 1594.4 cm-1 (II,II), 1592.0 cm-1 (II,III) and 1586.5 cm-1 (III,III). Substantial loss of bound acetate occurs at much lower water content (<0.5% v/v) in the III,III state than in the II,II and II,III states (>10%). The ligand-exchange reactions do not initially reduce the overall charge of the complex but facilitate further oxidation by proton-coupled electron transfer as the water-derived ligands are increasingly deprotonated in higher oxidation states. In the IR spectra deprotonation could be followed by the formation of acetic acid (DOAc, ~1725 cm-1, V(C-O)) from the released acetate (1573.6 cm-1, Vas(C-O)). By the on-line combination of an electrochemical flow cell with ESI-MS several product complexes could be identified. A di-u-oxo bridged III,IV dimer [Mn2(bpmp)(u-O)2]2+ (m/z 335.8) can be generated at potentials below the III,III/II,III couple of the di-u-acetato complex (0.61 V Vs. ferrocene). The ligand-exchange reactions allow for three metal-centered oxidation steps to occur from II,II to III,IV in a potential range of only 0.5 V, explaining the formation of a spin-coupled III,IV dimer by photo-oxidation with [Ru(bpy)3]3+ in previous EPR studies.

  • 223. Yanagisawa, Masaru
    et al.
    Korodi, Ferenc
    Bergquist, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry. Analytical Chemistry. Analytisk kemi.
    Holmberg, Anna
    Hagfeldt, Anders
    Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry. Analytical Chemistry.
    Åkermark, Björn
    Sun, Licheng
    Synthesis of phthalocyanines with two carboxylic acid groups and their utilization in solar cells based on nano-structured TiO22004In: Journal of Porphyrins and Phthalocyanines, Vol. 8, no 10, p. 1228-1235Article in journal (Refereed)
  • 224.
    Zettersten, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    On-line Electrochemistry Electrospray Ionisation Mass Spectrometry: Method Development and Applications2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with studies of on-line electrochemistry electrospray ionisation mass spectrometry (EC/ESI-MS). It is shown that the use of EC/ESI-MS demands optimal coupling characteristics.

    Pre-concentration and desalting, due to matrix exchange, were demonstrated for the model substance 1-hexanethiol in an EC/ESI-MS setup. The setup was also used for investigations of the oxidation states of the manganese complex [Mn2(bpmp)(µ-OAc)2][ClO4], where bpmp is a 2,6-bis[[N,N-di(2-pyridylmethyl)amino]methyl]-4-methylphenol compound. The manganese complex, which is relevant to artificial photosynthesis, was found to be a good model compound for the EC/ESI-MS studies, thanks to its many oxidation states. For the first time, the presence of the Mn(III,IV) state of the manganese complex was demonstrated in the studies.

    During the experimental work, the importance of the electrode positioning within the electrochemical cell was investigated. Different EC cell configurations were studied using the manganese complex as a model substance. It was clearly shown that the EC cell design influences the distribution between the peaks in the mass spectra - not only for manganese complexes and Olsalazine but also for 4-chloroaniline.

    A previously unknown comproportionation reaction was found for 4-chloroaniline involving the oxidised dimer, 4-[(4-chlorophenyl)imino]-2,5-cyclohexadien-1-imine. This reaction explained the unexpected presence of the signal due to the reduced dimer, 4-amino-4'-chlorodiphenylamine, in the mass spectra.

    Furthermore, it was shown that EC/ESI-MS was successful in conjunction with miniaturised gold wire electrodes in a PDMS chip within which dopamine was oxidised with a conversion efficiency of 30%. The oxidation products of dopamine were detected after 0.6-1.2 seconds for 1.0 and 0.5 µl/min, respectively. The combination of electrochemically controlled solid-phase extraction (EC-SPE) with ESI-MS was found to be less straightforward than detecting anions pre-concentrated on a polypyrrole coated electrode with EC-SPE/ICP-MS.

    The on-line combination of liquid chromatography with EC/ESI-MS/MS for studying antioxidants in yellow onion extracts was shown to be fast and a relatively easy complement to classical antioxidant activity determinations.

    List of papers
    1. A Setup for the Coupling of a Thin-Layer Electrochemical Flow Cell to Electrospray Mass Spectrometry
    Open this publication in new window or tab >>A Setup for the Coupling of a Thin-Layer Electrochemical Flow Cell to Electrospray Mass Spectrometry
    2004 (English)In: Analytical Chemistry, Vol. 76, no 7, p. 2017-2024Article in journal (Refereed) Published
    Abstract [en]

    A novel setup for the coupling of commercially available thin-layer cell to electrospray mass spectrometry (ESI-MS) which allows the elctrochemical reactions at the counter electrode to be straightforwardly separated from the flow into the mass spectrometer has been developed. In this way interferences from reaction products formed at the counter electrode can be minimized. This reduces the risk of changes in the mass spectra as a result of electrochemical reactions in the solution. The described setup also enables the working electrode to be positioned close to the electrospray (ESI) emitter without the need for a grounding point or a long transfer line between the electrochemical cell and the electrospray emitter. By decoupling the electrochemical reactions in the flow cell and those in the electrospray emitter, improved facilities for studies of electrochemical reactions are obtained through a better control of the potential of the working electrode. The setup has been used to study the oxidation of a drug (Olsalazine), which previously has been found to involve chemical follow-up reactions. It is also demonstrated that uncharged thiols can be detected in ESI-MS after spontaneous adsorption on a gold working electrode, followed by oxidative desorption to yield sulfinates or sulfonates. This adsorption and potential-controlled desorption has been used for the preconcentration of micromolar concentrations of 1-hexanethiol as well as for desalting of solutions containing micromolar concentrations of thiols. The results indicate that the present on-line coupling of an electrochemical cell to ESI-MS provides promising possibilities for sample preconcentration, matrix exchange (including desalting), and ionization of neutral compounds, such as thiols.

    Identifiers
    urn:nbn:se:uu:diva-70661 (URN)
    Available from: 2005-04-26 Created: 2005-04-26 Last updated: 2011-03-25
    2. Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.
    Open this publication in new window or tab >>Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.
    Show others...
    2005 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 6, p. 1033-1041Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-95874 (URN)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14
    3. On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry
    Open this publication in new window or tab >>On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry
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    2005 (English)In: Lab on a Chip, no 5, p. 1008-1016Article in journal (Refereed) Published
    Abstract [en]

    A novel method for the manufacturing of microchips for on-chip combinations of electrochemistry (EC) and sheathless electrospray ionisation mass spectrometry (ESI-MS) is described. The technique, which does not require access to clean-room facilities, is based on the incorporation of an array of gold microcoil electrodes into a poly(dimethylsiloxane) (PDMS) microflow channel equipped with an integrated graphite based sheathless ESI emitter. Electrochemical measurements, which were employed to determine the electroactive area of the electrodes and to test the microchips, show that the manufacturing process was reproducible and that the important interelectrode distance in the electrochemical cell could to be adequately controlled. The EC-ESI-MS device was evaluated based on the ESI-MS detection of the oxidation products of dopamine. The results demonstrate that the present on-chip approach enables full potentiostatic control of the electrochemical cell and the attainment of very short transfer times between the electrochemical cell and the electrospray emitter. The transfer times were 0.6 and 1.2 s for flow rates of 1.0 and 0.5 uL min-1, respectively, while the electrochemical conversion efficiency of the electrochemical cell was found to be 30% at a flow rate of 0.5 uL min-1. To decouple the electrochemical cell from the ESI-MS high voltage and to increase the user-friendliness, the on-line electrochemistry-ESI-MS experiments were performed using a wireless Bluetooth battery-powered instrument with the chip floating at the potential induced by the ESI high voltage. The described on-chip EC-ESI-MS device can be used for fundamental electrochemical investigations as well as for applications based on the use of electrochemically controlled sample pretreatment, preconcentration and ionisation steps prior to ESI-MS.

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-74547 (URN)doi:10.1039/b506289f (DOI)
    Available from: 2007-03-28 Created: 2007-03-28 Last updated: 2011-01-11
    4. On-line electrochemically controlled solid-phase extraction interfaced to electrospray and inductively coupled plasma mass spectrometry
    Open this publication in new window or tab >>On-line electrochemically controlled solid-phase extraction interfaced to electrospray and inductively coupled plasma mass spectrometry
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    2005 In: The Analyst, ISSN 0003-2654, Vol. 130, no 10, p. 1358-1368Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-96097 (URN)
    Available from: 2007-09-04 Created: 2007-09-04Bibliographically approved
    5. The influence of the thin-layer flow cell design on the mass spectra when coupling electrochemistry to electrospray ionisation mass spectrometry
    Open this publication in new window or tab >>The influence of the thin-layer flow cell design on the mass spectra when coupling electrochemistry to electrospray ionisation mass spectrometry
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    2006 (English)In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 590, no 1, p. 90-99Article in journal (Refereed) Published
    Abstract [en]

    The influence of the flow cell configuration on the mass spectra obtained when coupling an electrochemical thin-layer flow cell to electrospray mass spectrometry (ESI-MS) has been investigated. It is shown that interferences due to the electrochemical reaction on the counter electrode and/or the absence of 100% conversion efficiency can alter the mass spectra when conventional thin-layer flow cells are used in conjunction with ESI-MS. The effects, which affect the intensities and distribution of the peaks in the mass spectra, can result in the inability to detect products formed at the working electrode. Comparisons of mass spectra, generated after the electrochemical oxidation of a dinuclear Mn complex (where bpmp = 2,6-bis[bis(2-pyridylmethyl) amino]methyl-4-methylphenol) using two different thin-layer flow cells clearly show that the potential dependence and appearance of the mass spectra depend on the flow cell configuration used. The use of a modified thin-layer flow cell, in which the counter electrode had been separated from the working electrode, gave rise to significantly increased intensities for the oxidised MnIII,IV state of the complex. With the conventional unmodified cell, the corresponding complex was only seen for considerably higher oxidation potentials. The different results can be explained by the reduced risk of redox cycling and interferences due to species generated at the counter electrode with the modified cell. As interferences due to the counter electrode reactions likewise may be expected with many coulometric flow cells, the electrochemical cell design clearly needs to be considered when using electrochemistry coupled to ESI-MS to study electrochemical reactions.

    Keywords
    Electrochemistry, Electrospray ionisation mass spectrometry, Thin-layer cells, Flow cell design, Binuclear manganese complexes, Oxidation
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-82120 (URN)doi:10.1016/j.jelechem.2006.02.028 (DOI)
    Available from: 2007-03-06 Created: 2007-03-06 Last updated: 2017-12-14Bibliographically approved
    6. Oxidation of 4-chloroaniline studied by on-line electrochemistry electrospray ionization mass spectrometry
    Open this publication in new window or tab >>Oxidation of 4-chloroaniline studied by on-line electrochemistry electrospray ionization mass spectrometry
    2009 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 13, p. 5180-5187Article in journal (Refereed) Published
    Abstract [en]

    The oxidation of 4-chloroaniline (4-CA) has been studied by electrochemistry (EC) coupled on-line with electrospray ionization mass spectrometry (ESI-MS) using two electrochemical flow cells of different design. The experimental results, which generally verify previously suggested oxidation pathways for 4-CA, also indicate the presence of a so far unrecognized comproportionation reaction. The oxidation of 4-CA (m/z 128.2) was found to give rise to the formation of both an oxidized dimer, 4-[(4-chlorophenyl)imino]-2,5-cyclohexadien-1-imine (m/z 217.2) and a reduced dimer, 4-amino-4’-chlorodiphenylamine (m/z 219.2), in addition to a dimer intermediate (m/z 253.2). This unexpected formation of the reduced dimer is shown to stem from a comproportionation reaction involving 4-CA and the oxidized dimer. The presence of the latter reaction was clearly seen by comparing results obtained with two thin-layer flow cells, both with conversion efficiencies of 50% but of different design, with respect to the influence of the counter electrode reaction on the reaction at the working electrode. The experimental results demonstrate that the formation of the reduced dimer is favored by a decrease in the local pH in the flow cell and the influence of the pH on the oxidation of 4-CA was also investigated in the pH range between 2.0 and 6.0 using off-line voltammetry. It is concluded that EC/ESI-MS is a powerful tool for the study of the present type of reactions and that studies on reaction pathways are best carried out with thin-layer flow cells having conversion efficiencies smaller than 100% as this facilitates the detection of reaction intermediates. Comproportionation reactions, similar to the reaction present in the 4-CA system, can also be expected to be present during the formation of conducting polymers such as polyaniline and polypyrrole.

    Keywords
    4-chloroaniline, oxidation, electrochemistry, electrospray ionization mass spectrometry, reaction pathway, (p-chlorophenyl)aniline
    National Category
    Chemical Sciences
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-99325 (URN)10.1021/ac802563f (DOI)000267609500013 ()19563209 (PubMedID)
    Available from: 2009-03-12 Created: 2009-03-12 Last updated: 2018-06-26Bibliographically approved
    7. Identification and Characterization of Polyphenolic Antioxidants Using On-Line Liquid Chromatography, Electrochemistry, and Electrospray Ionization Tandem Mass Spectrometry
    Open this publication in new window or tab >>Identification and Characterization of Polyphenolic Antioxidants Using On-Line Liquid Chromatography, Electrochemistry, and Electrospray Ionization Tandem Mass Spectrometry
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    2009 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 21, p. 8968-8977Article in journal (Refereed) Published
    Abstract [en]

    It is demonstrated that electrochemistry (EC) coupled to liquid chromatography (LC) and electrospray ionization tandem mass spectrometry (LC/EC/ESI-MS/MS) can be used to rapidly obtain information about the antioxidant activity (i.e., oxidation potential) and capacity (i.e., amount) of polyphenolic compounds, including catechin, kaempferol, resveratrol, quercetin, and quercetin glucosides. The described on-line LC/EC/ESI-MS/MS method facilitates the detection and characterization of individual antioxidants based on a combination of the obtained m/z values for the antioxidants and their oxidation products, the potential dependences for the ion intensities, and correlations between the retention times in the LC, EC, and MS chromatograms. As these results provide patterns that can be used in rapid screening for antioxidants in complex samples, the method should be a valuable complement to chemical assays commonly used to determine the total antioxidant capacity of samples. It is shown that the antioxidant capacity for a mixture of polyphenolic compounds depends on the redox potential employed in the evaluation, and this should consequently be taken into account when comparing results from different total antioxidant capacity assays. It is also demonstrated that the inherent antioxidant capacities of phenolic compounds increase with an increasing number of hydroxyl groups and that the potential needed to oxidize the remaining hydroxyl groups increases successively upon oxidation of the compound. Unlike chemical assays, which generally do not provide any information about the identities of the compounds on the molecular level, the present screening method can be used to identify individual antioxidants, rank compounds with respect to their ease of oxidation, and to study the antioxidant capacity at any redox potential of interest.

    National Category
    Analytical Chemistry Inorganic Chemistry
    Research subject
    Analytical Chemistry; Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-99328 (URN)10.1021/ac901397c (DOI)000276191900046 ()
    Available from: 2009-03-12 Created: 2009-03-12 Last updated: 2018-06-26Bibliographically approved
  • 225.
    Zettersten, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Co, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wende, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Turner, Charlotta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Identification and Characterization of Polyphenolic Antioxidants Using On-Line Liquid Chromatography, Electrochemistry, and Electrospray Ionization Tandem Mass Spectrometry2009In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 21, p. 8968-8977Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that electrochemistry (EC) coupled to liquid chromatography (LC) and electrospray ionization tandem mass spectrometry (LC/EC/ESI-MS/MS) can be used to rapidly obtain information about the antioxidant activity (i.e., oxidation potential) and capacity (i.e., amount) of polyphenolic compounds, including catechin, kaempferol, resveratrol, quercetin, and quercetin glucosides. The described on-line LC/EC/ESI-MS/MS method facilitates the detection and characterization of individual antioxidants based on a combination of the obtained m/z values for the antioxidants and their oxidation products, the potential dependences for the ion intensities, and correlations between the retention times in the LC, EC, and MS chromatograms. As these results provide patterns that can be used in rapid screening for antioxidants in complex samples, the method should be a valuable complement to chemical assays commonly used to determine the total antioxidant capacity of samples. It is shown that the antioxidant capacity for a mixture of polyphenolic compounds depends on the redox potential employed in the evaluation, and this should consequently be taken into account when comparing results from different total antioxidant capacity assays. It is also demonstrated that the inherent antioxidant capacities of phenolic compounds increase with an increasing number of hydroxyl groups and that the potential needed to oxidize the remaining hydroxyl groups increases successively upon oxidation of the compound. Unlike chemical assays, which generally do not provide any information about the identities of the compounds on the molecular level, the present screening method can be used to identify individual antioxidants, rank compounds with respect to their ease of oxidation, and to study the antioxidant capacity at any redox potential of interest.

  • 226.
    Zhang, Qi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Norberg, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Baltzer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Synthesis of C-11 linked active ester derivatives of vitamin D3 and their conjugations to 42-residue helix–loop–helix peptides2010In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 66, no 25, p. 4577-4586Article in journal (Refereed)
    Abstract [en]

    Derivatives of vitamin D3 carrying an 8-carbon linker at C-11 terminating in an active ester were synthesized from commercial vitamin D3 using a disassembly- ereassembly strategy. Vitamin D3 was cleaved at the C6-C7 double bond and the ‘upper’ fragment was converted, via a series of reactions, to derivatives substituted at C-11 with an 8-carbon linker terminating in an ethyl ester. Reassembly with modified ‘lower’ fragments using Horner-Wittig olefination followed by linker ester hydrolysis and reesterification with p-nitrophenol gave C-11 substituted p-nitrophenyl esters. These vitamin D derivatives were conjugated to 42-amino acid helix-loop-helix peptides by reaction of their p-nitrophenyl esters with lysyl side-chain amino groups on the peptides. The vitamin D-peptide conjugates, being potential specific binder candidates forvitamin D-binding protein, were characterized by mass spectroscopy and CD measurements.

  • 227.
    Zuberovic, Aida
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Surface Modified Capillaries in Capillary Electrophoresis Coupled to Mass Spectrometry: Method Development and Exploration of the Potential of Capillary Electrophoresis as a Proteomic Tool2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increased knowledge about the complexity of the physiological processes increases the demand on the analytical techniques employed to explore them. A comprehensive analysis of the entire sample content is today the most common approach to investigate the molecular interplay behind a physiological deviation. For this purpose a method that offers a number of important properties, such as speed and simplicity, high resolution and sensitivity, minimal sample volume requirements, cost efficiency and robustness, possibility of automation, high-throughput and wide application range of analysis is requested. Capillary electrophoresis (CE) coupled to mass spectrometry (MS) has a great potential and fulfils many of these criteria. However, further developments and improvements of these techniques and their combination are required to meet the challenges of complex biological samples.

    Protein analysis using CE is a challenging task due to protein adsorption to the negatively charged fused-silica capillary wall. This is especially emphasised with increased basicity and size of proteins and peptides. In this thesis, the adsorption problem was addressed by using an in-house developed physically adsorbed polyamine coating, named PolyE-323. The coating procedure is fast and simple that generates a coating stable over a wide pH range, 2-11. By coupling PolyE-323 modified capillaries to MS, either using electrospray ionisation (ESI) or matrix-assisted laser desorption/ionisation (MALDI), successful analysis of peptides, proteins and complex samples, such as protein digests and crude human body fluids were obtained. The possibilities of using CE-MALDI-MS/MS as a proteomic tool, combined with a proper sample preparation, are further demonstrated by applying high-abundant protein depletion in combination with a peptide derivatisation step or isoelectric focusing (IEF). These approaches were applied in profiling of the proteomes of human cerebrospinal fluid (CSF) and human follicular fluid (hFF), respectively. Finally, a multiplexed quantitative proteomic analysis was performed on a set of ventricular cerebrospinal fluid (vCSF) samples from a patient with traumatic brain injury (TBI) to follow relative changes in protein patterns during the recovery process.

    The results presented in this thesis confirm the potential of CE, in combination with MS, as a valuable choice in the analysis of complex biological samples and clinical applications.

    List of papers
    1. Novel polyamine coating providing non-covalent deactivation and reversed electroosmotic flow of fused-silica capillaries for capillary electrophoresis
    Open this publication in new window or tab >>Novel polyamine coating providing non-covalent deactivation and reversed electroosmotic flow of fused-silica capillaries for capillary electrophoresis
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    2003 (English)In: Journal of Chromatography A, ISSN 0021-9673, Vol. 1003, p. 217-221Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-98064 (URN)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2009-03-24Bibliographically approved
    2. A polyamine coating for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry of proteins and peptides.
    Open this publication in new window or tab >>A polyamine coating for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry of proteins and peptides.
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    2004 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 13, p. 2090-2099Article in journal (Refereed) Published
    Abstract [en]

    A procedure for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) of proteins is presented. The use of a newly presented capillary coating, PolyE-323, provided fast separations of typically a few minutes with high efficiency, good deactivation, and no bleeding into the mass spectrometer. Capillaries coated with PolyE-323 showed high stability over a range of pH 2-10, and tolerance towards methanol and acetonitrile, two modifiers commonly used in CE-ESI-MS. Due to the speed and simplicity of the coating procedure, the polymeric surface could, if necessary, easily be regenerated. This capability is especially valuable when working with samples of complex matrix, where a capillary surface cleaning step might be desired in order to eliminate possible memory effects. The potential of PolyE-323-coated capillaries in bioanalysis using CE-ESI-MS was demonstrated by analyzing peptides and proteins up to 66 kDa using time of flight (TOF)-MS. Due to the stable, anodal electroosmotic flow generated by the coating, the use of a sheathless ESI interface was enabled, demonstrated in peptide analysis with attomole sensitivity. The fast on-line CE-ESI-TOF system using PolyE-323-coated capillaries provided efficient separation and detection of a large number of peaks in a short time, exemplified by the analysis of a tryptic digest of bovine serum albumin (BSA). The capability of the developed capillary surface coating was demonstrated by the separation of human plasma and cerebrospinal fluid (CSF).

    Keywords
    Capillary electrophoresis, mass spectrometry, peptides, polyamine coating, proteins
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-98065 (URN)10.1002/elps.200305787 (DOI)000222890600019 ()15237410 (PubMedID)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2017-12-13Bibliographically approved
    3. Capillary electrophoresis off-line matrix-assisted laser desorption/ionisation mass spectrometry of intact and digested proteins using cationic-coated capillaries
    Open this publication in new window or tab >>Capillary electrophoresis off-line matrix-assisted laser desorption/ionisation mass spectrometry of intact and digested proteins using cationic-coated capillaries
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    2004 (English)In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 18, no 23, p. 2946-2952Article in journal (Refereed) Published
    Abstract [en]

    Capillary electrophoresis (CE) was coupled off-line with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the analysis of proteins and peptides. CE fractions were collected directly on a matrix-coated MALDI target, using a sheath-flow interface. Protein adsorption during CE separations was prevented by coating the capillaries with the physically adsorbed, cationic polymer PolyE-323. The CE/MALDI-MS system was used for the analysis of model proteins and peptides at physiological pH as well as analysis of proteins in tear fluid. Moreover, tryptic on-target digestion of the collected protein fractions, with subsequent MALDI-MS and MS/MS peptide analysis, was demonstrated.

    National Category
    Chemical Sciences Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-98066 (URN)10.1002/rcm.1712 (DOI)15529414 (PubMedID)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2017-12-13Bibliographically approved
    4. Proteome profiling of human cerebrospinal fluid: exploring the potential of capillary electrophoresis with surface modified capillaries for analysis of complex biological samples.
    Open this publication in new window or tab >>Proteome profiling of human cerebrospinal fluid: exploring the potential of capillary electrophoresis with surface modified capillaries for analysis of complex biological samples.
    Show others...
    2008 (English)In: European journal of mass spectrometry, ISSN 1469-0667, E-ISSN 1751-6838, Vol. 14, no 4, p. 249-260Article in journal (Refereed) Published
    Abstract [en]

    A bottom-up proteomic approach, based on capillary electrophoresis (CE) in combination with matrix- assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-ToF/ToF MS), was used to analyze immunoaffinity depleted human cerebrospinal fluid (CSF) and compare it with a non-depleted sample. After enzymatic digestion and desalting, the tryptic peptides were separated by CE using PolyE-323 modified capillaries and fractionated off-line onto MALDI target plates for further analysis by MALDI-MS and MS/MS. The protein profile of the depleted sample was compared with non depleted CSF. Overall, 85 proteins were identified with 95% significance in both samples. The significance scores for proposed biomarkers, such as amyloid-like protein 1 precursor, could be increased up to 12 times after the depletion. Other proteins, often suggested to be related to neurodegenerative diseases, like amyloid beta A4 protein precursor, superoxide dismutase and apolipoprotein E precursor could only be found in the depleted CSF samples. The effect of a derivatization of tryptic peptides with 2- methoxy-4,5-dihydro-1H-imidazole reagent for protein identification with MS was also employed to increase the number of identified proteins and the sequence coverages. The results presented in this study illustrate the benefit of combining a sample pre-fractionation step and a label's ability to enhance the ionization efficiency with the potential of CE using PolyE-323 modified capillaries in the analysis of complex samples. The straight-forward approach that provides speed and simplicity resulting in high-resolution separations and low sample consumption represents an easily applicable separation technique that can serve as a complement to other currently existing analytical approaches needed in modern proteomic analysis of clinically relevant samples.

    Keywords
    CE, MALDI-MS/MS, CSF, proteomics, peptides, immunoaffinity depletion, chemical modification
    National Category
    Other Basic Medicine
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-98067 (URN)10.1255/ejms.929 (DOI)000259337500005 ()18756023 (PubMedID)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2018-01-13Bibliographically approved
    5. Surface modified capillary electrophoresis combined with in solution isoelectric focusing and MALDI-TOF/TOF MS: A gel-free multidimensional electrophoresis approach for proteomic profiling — Exemplified on human follicular fluid
    Open this publication in new window or tab >>Surface modified capillary electrophoresis combined with in solution isoelectric focusing and MALDI-TOF/TOF MS: A gel-free multidimensional electrophoresis approach for proteomic profiling — Exemplified on human follicular fluid
    2009 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 17, p. 3621-3628Article in journal (Refereed) Published
    Abstract [en]

    Development of miniaturized analytical tools continues to be of great interest to face the challenges in proteomic analysis of complex biological samples such as human body fluids. In the light of these challenges, special emphasis is put on the speed and simplicity of newly designed technological approaches as well as the need for cost efficiency and low sample consumption. In this study, we present an alternative multidimensional bottom-up approach for proteomic profiling for fast, efficient and sensitive protein analysis in complex biological matrices. The presented setup was based on sample pre-fractionation using microscale in solution isoelectric focusing (IEF) followed by tryptic digestion and subsequent capillary electrophoresis (CE) coupled off-line to matrix assisted laser desorption/ionization time of flight tandem mass spectrometry (MALDI TOF MS/MS). For high performance CE-separation, PolyE-323 modified capillaries were applied to minimize analyte-wall interactions. The potential of the analytical setup was demonstrated on human follicular fluid (hFF) representing a typical complex human body fluid with clinical implication. The obtained results show significant identification of 73 unique proteins (identified at 95% significance level), including mostly acute phase proteins but also protein identities that are well known to be extensively involved in follicular development.

    Keywords
    CE, Human follicular fluid (hFF), MALDI TOF MS/MS, Proteomics, Solution phase IEF
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-98068 (URN)10.1016/j.chroma.2008.12.026 (DOI)000265467200005 ()19155017 (PubMedID)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2017-12-13Bibliographically approved
    6. CE MALDI-TOF/TOF MS for multiplexed quantification of proteins in human ventricular cerebrospinal fluid
    Open this publication in new window or tab >>CE MALDI-TOF/TOF MS for multiplexed quantification of proteins in human ventricular cerebrospinal fluid
    2009 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 30, no 10, p. 1836-1843Article in journal (Refereed) Published
    Abstract [en]

    CE, interfaced off-line to MALDI-TOF/TOF MS, was for the first time used to quantitatively monitor the protein content in complex   biological and clinical samples with iTRAQ (TM) labeling. The   usefulness and advantage of iTRAQ (TM) labeling, in combination, with   CE MALDI-TOF/TOF MS is demonstrated on mixtures of protein standards and by a case study on human ventricular cerebrospinal fluid samples collected from a patient with traumatic brain injury during patient recovery. Mixtures of five standard proteins were initially analyzed to optimize the experimental conditions for the CE MALDI-MS and MS/MS  analysis. The interactions of proteins and peptides with the capillary   inner wall during CE separation were minimized using PolyE-323 modified  capillaries. The analysis of the ventricular cerebrospinal fluid   samples yielded 43 significantly (p < 0.05 MudPIT scoring) identified   proteins that could be quantitatively monitored over time. The identified changes in protein levels for several of these proteins are well in line with the reports from previous studies on protein patterns that could be related to the post-traumatic processes of traumatic brain injury. This study shows that the presented approach, combining  isobaric tags with CE MALDI-TOF/TOF MS, is a useful choice for quantitative proteomic analysis.

    Keywords
    CE MALDI-TOF/TOF MS, iTRAQ (TM), Multiplexed quantification, Proteomics, Ventricular cerebrospinal fluid
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-98069 (URN)10.1002/elps.200800714 (DOI)000266524500026 ()19441030 (PubMedID)
    Available from: 2009-02-20 Created: 2009-02-06 Last updated: 2017-12-13Bibliographically approved
  • 228.
    Zuberovic, Aida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Hanrieder, Jörg
    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.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    CE-MALDI-MS/MS for Proteomic Profiling and Multiplexed Quantification of Human Cerebrospinal Fluid (CSF)2007Conference paper (Other academic)
  • 229.
    Zuberovic, Aida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Hanrieder, Jörg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Hellman, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Proteome profiling of human cerebrospinal fluid: exploring the potential of capillary electrophoresis with surface modified capillaries for analysis of complex biological samples.2008<