| 1. |
- Both, P., et al.
(författare)
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Discrimination of epimeric glycans and glycopeptides using IM-MS and its potential for carbohydrate sequencing
- 2014
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Ingår i: Nature Chemistry. - 1755-4330 .- 1755-4349. ; 6:1, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectrometry is the primary analytical technique used to characterize the complex oligosaccharides that decorate cell surfaces. Monosaccharide building blocks are often simple epimers, which when combined produce diastereomeric glycoconjugates indistinguishable by mass spectrometry. Structure elucidation frequently relies on assumptions that biosynthetic pathways are highly conserved. Here, we show that biosynthetic enzymes can display unexpected promiscuity, with human glycosyltransferase pp-a-GanT2 able to utilize both uridine diphosphate N-acetylglucosamine and uridine diphosphate N-acetylgalactosamine, leading to the synthesis of epimeric glycopeptides in vitro. Ion-mobility mass spectrometry ( IM-MS) was used to separate these structures and, significantly, enabled characterization of the attached glycan based on the drift times of the monosaccharide product ions generated following collision-induced dissociation. Finally, ion-mobility mass spectrometry following fragmentation was used to determine the nature of both the reducing and non-reducing glycans of a series of epimeric disaccharides and the branched pentasaccharide Man3 glycan, demonstrating that this technique may prove useful for the sequencing of complex oligosaccharides.
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| 2. |
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| 3. |
- Gray, Christopher J., et al.
(författare)
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Advancing Solutions to the Carbohydrate Sequencing Challenge
- 2019
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:37, s. 14463-14479
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Forskningsöversikt (refereegranskat)abstract
- Carbohydrates possess a variety of distinct features with stereochemistry playing a particularly important role in distinguishing their structure and function. Monosaccharide building blocks are defined by a high density of chiral centers. Additionally, the anomericity and regiochemistry of the glycosidic linkages carry important biological information. Any carbohydrate-sequencing method needs to be precise in determining all aspects of this stereodiversity. Recently, several advances have been made in developing fast and precise analytical techniques that have the potential to address the stereochemical complexity of carbohydrates. This perspective seeks to provide an overview of some of these emerging techniques, focusing on those that are based on NMR and MS-hybridized technologies including ion mobility spectrometry and IR spectroscopy.
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| 4. |
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| 5. |
- Sardzik, Robert, et al.
(författare)
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Chemoenzymatic Synthesis of O-Mannosylpeptides in Solution and on Solid Phase
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:10, s. 4521-4524
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Tidskriftsartikel (refereegranskat)abstract
- O-Mannosyl glycans are known to play an important role in regulating the function of alpha-dystroglycan (alpha-DG), as defective glycosylation is associated with various phenotypes of congenital muscular dystrophy. Despite the well-established biological significance of these glycans, questions regarding their precise molecular function remain unanswered. Further biological investigation will require synthetic methods for the generation of pure samples of homogeneous glycopeptides with diverse sequences. Here we describe the first total syntheses of glycopeptides containing the tetrasaccharide NeuNAc alpha 2-3Gal beta 1-4GlcNAc beta 1-2Man alpha, which is reported to be the most abundant O-mannosyl glycan on alpha-DG. Our approach is based on biomimetic stepwise assembly from the reducing end and also gives access to the naturally occurring mono-, di-, and trisaccharide substructures. In addition to the total synthesis, we have developed a one-pot enzymatic cascade leading to the rapid synthesis of the target tetrasaccharide. Finally, solid-phase synthesis of the desired glycopeptides directly on a gold microarray platform is described.
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