Studies on the glucomannan from Candida utilis. Part III. Immunochemical analysis of the glucomannan from Candida utilis.

A glucomannan isolated from a Candida utilis mutant having a new chemotype was further studied by inhibition of the homologous precipitin reaction with oligosaccharides obtained from the glucomannan by partial acid hydrolysis and controlled acetolysis. Oligosaccharides having at least two consecutive alpha-(1----2)-linked mannose residues at the non-reducing end and gluco-manno-pentasaccharide were effective inhibitors. Thus, it appears that the glucomannan had two groups of antigenic determinants, one corresponding to the side chains of two, three, and four mannose units connected by alpha-(1----2)-linkage, and the other corresponding to a side chain composed of an O-alpha-D-glucopyranosyl-(1----6)-O-alpha-D-mannopyranosyl- (1----2)-O-alpha-D-mannopyranosyl-(1----2)-D-mannose unit. These results support a probable structure of repeating units for the glucomannan presented previously. The relative susceptibility of intersaccharidic linkages to acid hydrolysis in the mannan is discussed.