Partial Purification of β-Mannanases from the Konjac Tubers and Their Substrate Specificity in Relation to the Structure of Konjac Glucomannan

Abstract

Two components of konjac βmannanases, 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 gel-filtration 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.