Studies on mannan and related compounds. V. Partial purification of .BETA.-mannanases from the konjac tubers and their substrate specificity in relation to the structure of konjac glucomannan.

Abstract

Two components of konjac β-mannanases, I and II, were purified by Amberlite CG-50 column chromatography and Sephadex G-100 and G-50 column chromatography. The enzyme preparations behaved as a homogeneous protein in ultracentrifugal analysis. Their molecular weights were estimated to be 32, 000 and 29, 000, respectively, by gelfiltration method. Kinetic studies of these β-mannanases indicated that the hydrolysis of konjac glucomannan, mannooligosaccharides and glucomannooligosaccharides proceeds in a random or an endowise mechanism, but the randomness of enzyme I is less than that of enzyme II. Both β-mannanase I and II hydrolyzed β-1, 4-mannooligosaccharides and glucomannooligosaccharides, but the mannosidic bonds linked to the glucose residues were attacked slightly easier than thoe between mannose residues. On the present and the previous results, a possible structure of the konjac glucomannan was proposed.