A glucomannan as an extracellular product of Candida utilis. II Structure of a glucomannan. Characterization of oligosaccharides obtained by partial hydrolysis.

Abstract

The structure of an extracellular glucomannan produced by Candida utilis was studied. Up to 15% hydrolysis of the glucomannan with the α-mannosidase isolated from Arthrobacter GJM-1 did not alter its viscosity. Sequential treatment of the glucomannan with periodate, borohydride and 0.1 N HCl gave a nondialyzable periodate resistant portion which amounted to 15% of the original glucomannan. The carbohydrate residue of the periodate resistant portion was found to consist only of mannose. Methylation analysis indicated that all the glucose residues in the molecule were doubly branched at the C 3 and C 4 positions, and the non-reducing ends were composed of only mannose. Partial hydrolysis of the glucomannan yielded di-(PHP 1, 2), tri-(PHP 3), tetra-(PHP 4) and pentasaccharides (PHP 5) which were isolated by TLC. They all contained one mole of glucose residue per mole of oligosaccharide. Arthrobacter α-mannosidase completely hydrolyzed PHP 1 to glucose and mannose, but did not hydrolyze PHP 2. In addition, the enzyme degraded PHP 3 and 4 into PHP 2 and mannose, and PHP 5 into mannose and a tetrasaccharide which did not correspond to any of the series PHP 1-5. The structures of these oligosaccharides were studied, by a joint analyses using methylation and α-mannosidase digestion.