The role of carbohydrate moiety on thermostability of cellulases from Humicola insolens YH-8.

Abstract

Two types of cellulases, Avicelase and CMCase, from a thermophilic fungus Humicola insolens YH-8 were glycoenzymes. Avicelase and CMCase contained 26.1% and 39.0%, respectively, of carbohydrate residues which consisted of mannose and N-acetylglucosamine. These enzymes, especially CMCase, showed remarkable thermal and pH-stability. The partial removal of the carbohydrate residues, 60Y. with mixed-glycosidase and 90% with periodate oxidation and Smith degradation, resulted in a significant decrease in thermal and pH-stability. The carbohydrate moiety was suggested to be a stabilizer of cellulases.