Studies on xylanase system of thermophilic fungi. III. Enzymatic properties of .BETA.-xylosidase from Malbranchea pulchella var. sulfurea No. 48.

Abstract

Some enzymatic properties of Malbranchea β-xylosidase were investigated. The β-xylosidase activity was inhibited by Hg²⁺, Zn²⁺, Cu²⁺, N-bromosuccinimide, p-chloromercuri-benzoate and sodium laurylsulfate, while this activity was activated by Ca²⁺. The enzyme released xylose as the end product even from 10% xylobiose solution without forming any xylooligosaccharides. The enzyme well acted on aryl-β-D-xylosides, but showed no activity on alkyl-β-D-xylosides, and it was practically free from glucosidase activity. The Km and V_max, values of this enzyme for xylobiose were calculated to be 2.86×10^-3M and 34.5 μmoles/mg/min, respectively, and these values determined for phenyl-β-D-xyloside were 3.01×10^-3M and 16.2 μmoles/mg/min, respectively.