Linkage Memory in Underivatized Protonated Carbohydrates

Abstract

<p>Carbohydrates are among the most complex class of biomolecules and even subtle variations in their structures are attributed to diverse biological function. Mass spectrometry has been essential for large scale glycomics and glycoproteomics studies, but the gas-phase structures and sometimes anomalous fragmentation properties of carbohydrates present longstanding challenges. Here we investigate the gas-phase properties of a panel of isomeric protonated disaccharides differing in their linkage configurations. Multiple conformations were evident for most of the structures based on their fragment ion abundances by tandem mass spectrometry, their ion mobilities in several gases, and their deuterium uptake kinetics by gas-phase hydrogen deuterium exchange. Most notably, we find that the properties of the Y-ion fragments are characteristically influenced by the precursor carbohydrate’s linkage configuration. This study reveals how protonated carbohydrate fragment ions can retain ‘linkage memory’ that provides structural insight into their intact precursor.</p>

A New Strategy Coupling Ion-Mobility-Selective CID and Cryogenic IR Spectroscopy to Identify Glycan Anomers

“…20−22 Such studies in which fragments generated by collision-induced dissociation (CID) are characterized by IMS have led to the identification of regioisomers and anomers of the precursor glycans. 23,24 Ultrahigh-resolution IMS has been able to separate subtle substructures in small glycans, 25−30 cyclic IMS instrument has recently been used to separate and partially identify the isomers of a set of pentasaccharides based on their fragmentation pattern. 28,29 However, the everincreasing resolution of IMS devices leads to the observation of multiple peaks in the arrival-time distribution (ATD).…”

Synthesis of an Exhaustive Library of Naturally Occurring Galf-Manp and Galp-Manp Disaccharides. Toward Fingerprinting According to Ring Size by Advanced Mass Spectrometry-Based IM-MS and IRMPD

“…Upon fragmentation, galactomannans will release specific disaccharidic fragments which fingerprints will match that of the synthetic library. The MS/MS strategy has been applied to the identification of the monosaccharide content (analyses were done on the monosaccharide fragments released upon fragmentation), [41][42][43] and IRMPD signatures of methyl furanoside and pyranoside derived from N-acetyl-galactosamine have been previously reported. 40 We anticipate however that monosaccharidic fragments may isomerize upon fragmentation, especially the thermodynamically less stable hexofuranosyl residues, and this would adversely affect the analysis of monosaccharide entities in larger oligosaccharides.…”