β-glucosidase of a white-rot fungus Trametes gibbosa

Extracellular beta-glucosidase was purified from a white-rot fungus, Trametes gibbosa by 50% ammonium sulphate saturation and Sephadex G-100 column chromatography. It showed maximum activity towards p-nitrophenyl- beta-D- glucopyranoside (pNpG). The pH optimum was 3.5. Temperature optimum was 40 degrees C but shifted to 50 degrees C on preincubation with pNpG. Hg 2+ , Fe 3+ and Cu 2+ strongly inhibited the activity. The enzyme was competitively inhibited by glucose with a Ki of 5.2 mM. The apparent molecular mass as determined by gel filtration chromatography was 640 kDa.