Crystallization and Some Properties of Mannanase

Abstract

A mannan-hydrolyzing enzyme produced by a certain strain of Bacillus subtilis was purified from the culture broth and isolated in a crystalline state by being treated with several ion-exchangers. The optimal pH of the enzyme was 6.0. The enzyme was stable in a pH region of 5.0 to 9.5 and at temperatures less than 55°C. The enzyme attacked only β-1,4-mannosidic linkages in the main chain of galactomannan of soybean seed coat, guar gum and coffee bean, and of glucomannan of konjak (Amorphophalus konjac). Investigation of the hydrolysis mode revealed that the enzyme attacked coffee bean galactomannan endowise to form mannobiose, mannotriose and mannotetraose. The action patterns on several mannohomooligomers prepared from a partial hydrolysate of coffee bean galactomannan were also investigated, indicating that the enzyme preferentially attacked the β-1,4-mannosidic linkages that were present apart three to four mannose residues from the non-reducing end of the mannose chain.