THE CONSTITUTION OF A HEMICELLULOSE FROM SUGAR MAPLE (ACER SACCHARUM)

Abstract

Partial hydrolysis of the main hemicellulose constituent of sugar maple (Acersaccharum) has yielded D-xylose, D-galacturonic acid, 4-O-methyl-D-glucuronic acid, and 2-O-(4-O-methyl-α-D-glucosyluronic acid)-D-xylose. Hydrolysis of the fully methylated polysaccharide gave a mixture of 2-O- and 3-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and 2-O-(2,3,4-tri-O-methyl-α-D-glucosyluronic acid)-3-O-methyl-D-xylose in a mole ratio of 3:111:1:12. The number-average degrees of polymerization of the native and the methylated polysaccharide were 205 and 149, respectively. These data indicate that the hemicellulose is composed of a linear chain of 1,4-linked β-D-xylose residues and that on the average every tenth residue of the chain carries a terminal 4-O-methyl-D-glucuronic acid residue attached through its C2. The structure of the polysaccharide is similar to that of the main hemicellulose component of European beech, white birch, and yellow birch.