Purification and characterization of a chitinase from Trichoderma viride

Abstract

Usukizyme, a commercial enzyme preparation from Trichoderma viride, showed multiple chitindegrading activities. One of these was purified to homogeneity by sequential DEAE Sepharose CL-6B, Q-Sepharose FF, and Sephacryl S-100 HR column chromatographies. The purified enzyme showed optimum activity at pH 3.5 and 50°-55°C and was stable in the pH range of 3.5-6.0 and up to 45°C. It showed higher activity toward chitosan-7B, a 62% deacetylated chitosan, as opposed to highly deacetylated chitosan substrates. Products of degradation of a 1% (w/v) solution of partially deacetylated chitin (PC-100) were purified on CM-Sephadex C-25 and analyzed by HPLC, exo-glycosidase digestion, and nitrous acid deamination. The enzyme was unable to split the GlcN-GlcN linkages in the substrate. It produced mainly (GlcNAc)2 and (GlcNAc)3 along with mixed oligosaccharides. When subjected to nitrous acid degradation, some of the mixed oligosaccharides produced mainly 2-deoxyglucitol, implying the presence of GlcN at the reducing end of the oligosaccharides.