Comparative Conformational Analysis of Acyclic Sugar Alcohols Ribitol, Xylitol and d-Arabitol by Solution NMR and Molecular Dynamics Simulations.

Ribitol (CHO) is an acyclic sugar alcohol that was recently identified in -mannose glycan on mammalian α-dystroglycan. The conformation and dynamics of acyclic sugar alcohols such as ribitol are dependent on the stereochemistry of the hydroxyl groups; however, the dynamics are not fully understood. To gain insights into the conformation and dynamics of sugar alcohols, we carried out comparative analyses of ribitol, d-arabitol and xylitol by a crystal structure database search, solution NMR analysis and molecular dynamics (MD) simulations.

Ribitol in Solution Is an Equilibrium of Asymmetric Conformations.

Ribitol (CHO), an acyclic sugar alcohol, is present on mammalian α-dystroglycan as a component of -mannose glycan. In this study, we examine the conformation and dynamics of ribitol by database analysis, experiments, and computational methods. Database analysis reveals that the anti-conformation (180°) is populated at the C3-C4 dihedral angle, while the gauche conformation (±60°) is seen at the C2-C3 dihedral angle.

Synthesis and Glycan-Protein Interaction Studies of -Sialosides by Se NMR.

To expand the potential of carbohydrates for multifunctional mimicry of sugars, herein we addressed the synthesis of the highly challenging and biologically significant glycosides of sialic acid (sialosides). An α-sialyl selenolate anion generated in situ smoothly reacted with electrophiles to give α-sialosides as single stereoisomers. A -sialoside was sequentially incorporated with selenium, producing a triseleno-sialoside.

Structural analysis of a novel lipooligosaccharide (LOS) from Rhodobacter azotoformans.

Lipopolysaccharides (LPS) are components of the Gram-negative bacterial cell surface that stimulate the host innate immune system through the Toll-like receptor (TLR) 4-MD-2 complex. Rhodobacter sp. have been reported to produce LPS that lack endotoxic activity, and instead act as antagonists of other endotoxins.

J( Se, H) and J( Se, C) couplings of seleno-carbohydrates obtained by Se satellite 1D C spectroscopy and Se selective HR-HMBC spectroscopy.

Seleno-carbohydrates are those in which the oxygen of the glycosidic bond or the hydroxyl group is artificially replaced with selenium. This substitution changes H and C chemical shifts and produces spin coupling constants involving Se. Coupling constants, such as J( Se, H), are likely to be useful for conformational analyses of glycans because such couplings are never observed in natural glycans.