Effect of monosaccharide composition, glycosidic linkage position and anomericity on the electrophoretic mobility of labeled oligosaccharides

Boronate affinity saccharide electrophoresis: a novel carbohydrate analysis tool

The incorporation of specialised carbohydrate affinity ligand methacrylamido phenylboronic acid in polyacrylamide gels for fluorophore-assisted carbohydrate electrophoresis greatly improved the effective separation of saccharides that show similar mobilities in standard electrophoresis. Polyacrylamide gel electrophoresis using methacrylamido phenylboronic acid in low loading (typically 0.5-1% dry weight) was unequivocally shown to alter retention of labelled saccharides depending on their boronate affinity. While conventional fluorophore-assisted carbohydrate electrophoresis of 2-aminoacridone labelled glucose oligomers showed an inverted parabolic migration, an undesired trait of small oligosaccharides labelled with this neutral fluorophore, boron affinity saccharide electrophoresis separation of these carbohydrates completely restored their predicted running order, based on their charge/mass ratio, and resulted in improved separation of the analyte saccharides. These results exemplify boron affinity saccharide electrophoresis as an important new technique for analysing carbohydrates and sugar-containing molecules.

Influence of outer region mannosylphosphorylation on N-glycan formation by Candida albicans: normal acid-stable N-glycan formation requires acid-labile mannosylphosphate addition

The pathogenic yeast Candida albicans produces large N-glycans with outer regions containing only mannose residues. The outer region comprises a primary branch with multiple secondary and tertiary branches. Tertiary branches are linked to secondary branches by phosphodiester bridges. In the current model of outer chain elongation in the genetically related yeast Saccharomyces cerevisiae, synthesis of the branches occurs sequentially, primary to tertiary. Thus, disruption of mannosylphosphorylation, the initial step in tertiary branch formation, should not affect primary or secondary branch production. Compared to its wild-type parent, a C. albicans mutant defective in tertiary branch mannosylphosphorylation (mnn4Delta/mnn4Delta) made outer regions with reduced susceptibility to low acid acetolysis treatment, suggesting that the secondary or primary region had been modified. Higher acid acetolysis conditions were required to release the secondary branches from the primary branches. The released secondary branches constitute the subset of the wild-type secondary branches that lack a phosphate group. In contrast, the acid-stable region of both wild-type and mnn4Delta S. cerevisiae strains required high acid acetolysis conditions to release the secondary branches, despite having smaller and less complex secondary and tertiary branches. These results suggest that the complex and longer secondary and tertiary branches of C. albicans affect the conformation of the acid-stable region to render it more susceptible to acetolysis which implies secondary and tertiary branch formation in C. albicans are interdependent events and occur concurrently, rather than sequentially.