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- Buijs, Jos, et al.
(författare)
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A new method for the accurate determination of the isotopic state of single amide hydrogens within peptides using Fourier transform ion cyclotron resonance mass spectrometry
- 2000
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Ingår i: Rapid Communications in Mass Spectrometry. - 0951-4198. ; 14:19, s. 1751-1756
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Tidskriftsartikel (refereegranskat)abstract
- A new method is presented to accurately determine the probability of having a deuterium or hydrogen atom on a specific amide position within a peptide after deuterium/hydrogen (D/H) exchange in solution. Amide hydrogen exchange has been proven to be a sensitive probe for studying protein structures and structural dynamics. At the same time, mass spectrometry in combination with physical fragmentation methods is commonly used to sequence proteins based on an amino acid residue specific mass analysis. In the present study it is demonstrated that the isotopic patterns of a series of peptide fragment ions obtained with capillary-skimmer dissociation, as observed with a 9.4 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer, can be used to calculate the isotopic state of specific amide hydrogens. This calculation is based on the experimentally observed isotopic patterns of two consecutive fragments and on the isotopic binomial distributions of the atoms in the residue constituting the difference between these two consecutive fragments. The applicability of the method is demonstrated by following the sequence-specific D/H exchange rate in solution of single amide hydrogens within some peptides.
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| 4. |
- Dahle, Charlotte, et al.
(författare)
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Antibodies against deamidated gliadin peptides identify adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase
- 2010
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Ingår i: Alimentary Pharmacology and Therapeutics. - : Blackwell Publishing Ltd. - 0269-2813 .- 1365-2036. ; 32:2, s. 254-260
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Tidskriftsartikel (refereegranskat)abstract
- Background This study was done to evaluate the diagnostic utility of antibodies against deamidated gliadin peptides compared to traditional markers for coeliac disease. Aim To evaluate diagnostic utility of antibodies against deamidated gliadin peptide (DGP). Methods Sera from 176 adults, referred for endoscopy without previous analysis of antibodies against tissue transglutaminase (tTG) or endomysium (EmA), were retrospectively analysed by ELISAs detecting IgA/IgG antibodies against DGP or a mixture of DGP and tTG, and compared with IgA-tTG and EmA. Seventy-nine individuals were diagnosed with coeliac disease. Results Receiver operating characteristic analyses verified the manufacturers cut-off limits except for IgA/IgG-DGP/ tTG. In sera without IgA deficiency, the sensitivity was higher for IgA/IgG-DGP (0.85-0.87) compared with IgA-tTg (0.76) and EmA (0.61). All tests showed high specificity (0.95-1.00). Eighteen coeliac disease-sera were negative regarding IgA-tTG, nine of which were positive for IgA/IgG-DGP. Sera from coeliac disease-patients greater than70 years were more often negative for IgA-tTG (50%) and IgA/IgG-DGP (36%) than younger patients (15% and 8% respectively) (P less than 0.01). Three of the four IgA-deficient patients were positive in the IgA/IgG-DGP assay. Conclusions In this study of patients unselected regarding IgA-tTg/EmA, thus unbiased in this respect, IgA/IgG-DGP identified adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase. Serology is often negative in elderly patients with coeliac disease; a small bowel biopsy should therefore be performed generously before coeliac disease is excluded.
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| 8. |
- Hagman, Charlotte, 1973-
(författare)
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Method Development in Quantitative and Structural Proteomics using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, methods for studying different aspects of proteomics were developed with Fourier Transform Ion Cyclotron Resonance, (FTICR), mass spectrometry. The FTICR technique provides ultra-high mass resolving power, mass accuracy at sub ppm level and sensitivity in the attomole region.Methods for quantifying biomarkers in body fluids such as cerebrospinal fluid, (CSF), and plasma were developed. Two sets of global markers with different properties were used for quantitative analysis; S-Methyl Thioacetimidate, (SMTA), and S-Methyl Thiopropionimidate, (SMTP), and [H4]- and [D4]-1-Nicotinoyloxy succinimide ester. Reduced ion suppression and higher sensitivity was obtained by coupling a High Performance Liquid Chromatography, (HPLC), system to the FTICR mass spectrometer.In body fluids, proteins and peptides are present in a broad dynamic concentration range. Therefore, depleting abundant proteins prior to analysis results in decreased ion suppression and increased sensitivity. Two commercial depletion kits were evaluated with the SMTA- and SMTP-markers.For both types of global markers, the experimental error for quantitative analysis of abundant proteins was less than 30%. This provides a lower limit for the protein up- and down regulations in complex solutions that can be monitored with HPLC-FTICR mass spectrometry.Together with the identity and quantity of selected proteins the structure, dynamics and interactions with other molecules are of great importance. The later can be elucidated with Hydrogen/Deuterium Exchange, (HDX), mass spectrometry. Structural information at high resolution can be obtained with Collision-Induced Dissociation, (CID), HDX mass spectrometry. In this thesis, exchange rates of amide hydrogens in peptides were in excellent agreement with NMR results.In some cases, the CID-fragments have different gas-phase exchange properties and as a consequence the solution phase exchange process can not be monitored. By applying Electron Capture Dissociation, (ECD), at ultra-high vacuum, the exchange process at a specific residue could be monitored.
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