Rationalization of Carbon-13 Magnetic Resonance Spectra of Yeast Mannans and Structurally Related Oligosaccharides

Abstract

The carbon-13 magnetic resonance (c.m.r.) spectra of oligosaccharides, derived from yeast mannans by partial acetolysis, contain signals at δ_C 93.1–105.4 (C-l's) and 79.2–81.2 (C-2's and/or C-3's substituted by mannopyranosyl units). They were assigned on the basis of (a) carbons deshielded by attached mannopyranosyl units have resonances at lower field than those of unsubstituted carbons and (b) comparison under carefully controlled conditions of the relative sizes of signals of comparable carbons, which have the same resonances, in members of two different homologous series of oligosaccharides. The c.m.r. spectra of certain mannans containing (1 → 6)-linked α-D-mannopyranose main-chains could then be rationalized since they have many signals with resonances in common with those of oligosaccharides, which are derived by partial acetolysis and contain the structures of the side chains.