Characterization of a new acid stable exo-β-1,3-glucanase of Rhizoctonia solani and its action on microbial polysaccharides

摘要

A new acid stable exo-β-1,3-glucanase of Rhizoctonia solani purified from a commercial source 'Kitarase　M', by a combination of ammonium sulfate precipitation, ion-exchange and gel filtration methods, had specific activity of 0.26 U/mg protein, K_m and V_max values of 0.78 mg/ml and 0.27 mM/min/mg protein, respectively. It had molecular weight of 62 kDa with optimum activity at 40 ℃ temperature and pH 5.0, with high stability at pH of 3-7. Unique amino acid sequence was found at N-terminal end. The substrate specificity studies confirmed that it is an exo-β-1,3-glucanase. It could hydrolyze curdlan powder to release glucose.