Abstract: Polygalacturonase is an enzyme that hydrolyzes D-galacturonic acid α-1,4- glucoside bond, which is of great significance in food industry, especially in fruit and vegetable processing. To exploit the biochemical properties of polygalacturonase produced from Trichoderma asperellum (14636), the polygalacturonase was isolated and purified by ammonium sulfate fractionation and dialysis method. Its molecular weight was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). According to the experimental results, the activation range of this enzyme was from 29.29 kDa to 50.46 kDa, the optimum pH was 4.0, it had good stability within pH 3.0-5.0; the optimum temperature was 40 ℃, and it showed certain thermal stability. The enzyme activity was higher in sodium acetate buffer. The catalytic properties showed that pectin was the optimal substrate for polygalacturonase, and the Km value was 0.74 mg/ml, Vmax was 3100 μg/min. Mn2+, Mg2+, Cu2+, Ca2+ and Tritonx-100 could activate this enzyme, and the activate effect of Ca2+ and Tritonx-100 were stronger; while Co2+, Zn2+, Ba2+, Li+, Fe2+, SDS and Tween-80 exerted different inhibitory effects on its activity. Storage characteristics showed that this enzyme retained more than 70% of its activity at 30 ℃ for 30 d. This study can provide a theoretical basis for the development of new enzyme preparations in the field of fruit and vegetable clean processing.
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