Simple Method for De Novo Structural Determination of Underivatised Glucose Oligosaccharides

Abstract

Carbohydrates have various functions in biological systems. However, the structural analysis of carbohydrates remains challenging. Most of the commonly used methods involve derivatization of carbohydrates or can only identify part of the structure. Here, we report a de novo method for completely structural identification of underivatised oligosaccharides. This method, which can provide assignments of linkages, anomeric configurations, and branch locations, entails low-energy collision-induced dissociation (CID) of sodium ion adducts that enable the cleavage of selective chemical bonds, a logical procedure to identify structurally decisive fragment ions for subsequent CID, and the specially prepared disaccharide CID spectrum databases. This method was first applied to determine the structures of four underivatised glucose oligosaccharides. Then, high-performance liquid chromatography and a mass spectrometer with a built-in logical procedure were established to demonstrate the capability of the in situ CID spectrum measurement and structural determination of the oligosaccharides in chromatogram. This consolidation provides a simple, rapid, sensitive method for the structural determination of glucose oligosaccharides, and applications to oligosaccharides containing hexoses other than glucose can be made provided the corresponding disaccharide databases are available.

Anti-Helicobacter Pylori Activity and Immunostimulatory Effect of Oligosaccharide Isolated From Averrhoa Carambola L.

“…Oligosaccharide as a secondary metabolite from star fruit was isolated using adsorption methods and partially characterized for the first time. Separation of carbohydrates is extensively carried out using high-pressure liquid chromatography while MS is a widely used tool to study its structure [31]. ESI is one of the common methods for carbohydrate analysis.…”

“…6c shows the deprotonated MS of the oligosaccharide. According to Domon and Costello nomenclature, a series of A and C type fragments ions are expected in MS at negative mode [31]. Hence, fragmentation could have started from the non-reducing end of the oligosaccharide.…”

Characterization and Analysis of Food-Sourced Carbohydrates

“…They are determined by the comparison of chromatography to that of databases which the structure of carbohydrates are characterized by other methods, for example, NMR and Mass spectrometry (MS). MS requires much less sample than that of NMR, which makes MS particularly useful for the structural analysis of limited amount of available samples, for example, the carbohydrates extracted from biological systems [84]. Added to that, the invention of ionization techniques such as fast-atom bombardment (FAB) electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) have helped contribute to the importance of MS in carbohydrate analysis.…”

“…Added to that, the invention of ionization techniques such as fast-atom bombardment (FAB) electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) have helped contribute to the importance of MS in carbohydrate analysis. The identification of carbohydrate structures via MS remains challenging due to the low ionzation efficiency of carbohydrates in a mass spectrometer [85], the large amount of carbohydrate isomers, and the similarity of mass spectra between isomers [84]. However, coupled with GC or LC as preseparation tools, MS is capable of separating isomeric ions based on retention times.…”

Unusual milk oligosaccharides and the biosynthetic pathways

“…Recently, a new mass spectrometry method, namely logically derived sequence (LODES) multistage tandem mass spectrometry (MS n ) was developed for the full structural determination of oligosaccharides [35][36][37][38] . This method can be used to determine oligosaccharide structures including linkage positions, anomericities, and monosaccharide stereoisomers.…”