Chapter 13 - Analytical approaches towards the structural characterization of microbial wall glycopolymers

Abstract

Glycans are structurally complex molecules and, as such, their structural characterization is a challenging task. The precise strategy to be applied is dictated by the level of information required and the expertise of the research team involved; however, the most comprehensive and informative studies employ aspects of enzymatic, chemical, chromatographic, MS, and NMR methods to complete the characterization process. This chapter outlines the strategies for the use of the analytical techniques of nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) toward the elucidation of the structures of microbial wall glycans. Specifically, the determination of the structure of capsular polysaccharide, core oligosaccharide or O-antigen utilizing 1D, 1D selective and 2D homonuclear, and heteronuclear NMR experiments and database resources is presented. Also described is the application of high-resolution magic angle spinning techniques for studying glycopolymer structures. MS sample derivatization strategies along with associated gas chromatography-mass spectrometry, sugar, linkage, and absolute configuration analyses are outlined. The use of fast atom bombardment, matrix-assisted laser desorption ionization, and electrospray-mass spectrometry ionization techniques along with their associated mass analyzers are presented for characterizing oligosaccharide, lipid A, lipooligosaccharide, lipopolysaccharide, and capsular polysaccharide glycan structures.