Structures of yeast mnnans containing both α- and β-linked D-mannopyranose units

Abstract

Several mannans from yeasts give proton magnetic resonance spectra with distinctive H-1 signals at higher field than τ 4.55. A number of these mannans were investigated polarimetrically and each has a specific rotation corresponding to a mixture of α- and β-D-linkages. Four were partially hydrolyzed and shown to have most of the α-linkages in the main chains and the β-linkages in the side chains. Detailed structural investigations showed that the Pichiapastoris mannan probably has an α-(1→6)-D-manno-pyranosyl main-chain substituted in the 2-positions with a substantial proportion of O-α-D-mannopy-ranosyl-(1→2)-O-β-D-mannopyranosyl-(1→2)-O-β-D-mannopyranosyl-(1→2)-O-α-mannopyranosyl side-chains (1). The related mannan from Citeromycesmatritensis has a similar main-chain, which is substituted in the 2-positions by α-D-mannopyranosyl units and β-(1→2)-pyranose-linked D-mannotriosyl and perhaps mannobiosyl side-chains (2).