Biochemical characterization of a 27 kDa 1,3-β-D-glucanase from Trichoderma asperellum induced by cell wall of Rhizoctonia solani

摘要

Trichoderma asperellum produces two extracellular 1,3-β-D-glucanase upon induction with cell walls from Rhizoctonia solani. A minor 1,3-β-D-glucanase was purified to homogeneity by ion exchange chromatography on Q-Sepharose and gel filtration on Sephacryl S-100. A typical procedure provided 13.8-fold purification with 70% yield. SDS-PAGE of the purified enzyme showed a single protein band of molecular weight 27 kDa. The enzyme exhibited optimum catalytic activity at pH 3.6 and 45 ℃. It was thermostable at 40 ℃, and retained 75% activity after 60 min at 45 ℃ The K_m and V_(max) values for 1,3-P-D-glucanase, using laminarin as substrate, were 0.323 mg ml~(-1) and 0.315 U min~(-1), respectively. The enzyme was strongly inhibited by Hg~(2+) and SDS. The enzyme was only active toward glucans containing β-1,3-linkages. Peptide sequences showed similarity with two endo-1,3(4)-β-D-glucanases from Aspergillus fumigatus Af293when compared against GenBank non-redundant database.