Structure and composition of the alkali-insoluble cell wall fraction of Coprinus macrorhizus var. microsporus

Abstract

The alkali-insoluble (R-) fraction from the cell walls of Coprinus macrorhizus var. microsporus is a highly branched glucan, containing alpha-(1 leads to 4), beta-(1 leads to 3), and beta-(1 leads to 6) linkages as shown by methylation, partial acid hydrolysis, and enzymic hydrolysis. The alpha-(1 leads to 4)-linked segments are joined by occasional beta-(1 leads to 3) links as suggested by the identification of 2-O-alpha-glucopyranosyl erythritol in the hydrolysate of the reduced, periodate-oxidized glucan. Hydrolysis of the permethylated glucan gave nearly equimolar amounts of 2,4-di- and 2,3-di-O-methyl-D-glucose. Methylation analysis of the residue from enzymic hydrolysis, the "CORE-fraction," indicated the presence of glucose residues in this fraction linked through positions O1, O3, O4, and O6. Hydrolysates of the R-fraction contained mannose, glucosamine, and amino acids in addition to glucose.