Purification and characterization of konjac glucomannan degrading enzyme from anaerobic human intestinal bacterium, Clostridium butyricum-Clostridium beijerinckii group.

Konjac glucomannan degrading enzyme was purified to homogeneity from the culture broth of an anaerobic human intestinal bacterium, Clostridium butyricum-Clostridium beijerinckii group. The enzyme was composed of a single polypeptide chain with a molecular weight of 50,000-53,000. The enzyme was an endo-beta-mannanase that acted specifically on the polysaccharides such as konjac glucomannan and coffee mannan, producing exclusively their smaller oligosaccharides and the monosaccharides. The optimal pH of the enzyme for the hydrolysis of konjac glucomannan was around 7-8 and the enzyme was stable in rather alkaline pH range of 8-10. The enzyme reaction was activated by the addition of CaCl2 and dithiothreitol. It was suggested that the enzyme might contribute to the decomposition of konjac glucomannan in human digestive tract.