STRUCTURE OF CELL-WALL GLUCAN OF YEAST - (SACCHAROMYCES CEREVISIAE)

The cell-wall D-glucan ({A figure is presented} -10° in methyl sulfoxide) of bakers' yeast has been shown by methylation and periodate oxidation studies to be a β-(1→3)-D-glucan having branches at C-6. Hyrdrolysis of the methylated D-glucan (1 mole) yielded 2,3,4,6-tetra- (1 mole), 1,2,4,6-tri- (7 moles), and 2,4-di-O-methyl-D-glucose (1 mole), and trace proportions of 2,3,4-tri-O-methyl-D-glucose, which indicated the presence of a small proportion of (1→6)-linked residues in the molecule. Periodate oxidation of the D-glucan (DP 410), followed by reduction and mild hydrolysis with acid, eliminated one D-glucose residue out of every 9, and yielded the corresponding, degraded D-glucan (DP 150), glycerol, and a small proportion of a 1-O-β-D-glucosylglycerol, which would be derived from the sequence of the D-glucose residues in the glucan molecule represented by the system →6)-Gp-(1→3)-Gp-(1→6)-Gp-(1→. Methylation of the degraded glucan gave material which, on hydrolysis, gave, per mole,2,3,4,6-tetra-(1 mole),2,4,6-tri-(6 moles),and 2,4-di-O-methyl-D-glucose(1 mole). The (1→3)-β-D-glucanase from Rhizopus arrhizus acted on the D-glucan and on the degraded D-glucan to give the same products, viz., D-glucose, laminaribiose, gentiobiose, and higher oligosaccharides. The structure of the cell-wall D-glucan is discussed on the basis of these findings. © 1968.