Characterization of polygalacturonase from tomato ( Lycopersicon Esculentum mill) fruits infected by Rhizopus arrhizus Fisher.

The production of polygalacturonase during the deterioration of tomato fruits by Rhizopus arrhizus Fisher. was investigated. The enzyme was partially purified by a combination of ammonium sulphate precipitation, gel filtration and ion-exchange chromatography. Optimum activity of the polygalacturonase was at 35 °C , pH 4.5 and the substrate concentration at half maximum velocity (km values ) for the hydrolysis of pectin by the polygalacturonase fractions (Da, Db and Ea ) were 3.8, 2.8 and 2.9 mg/ml. The enzyme was stimulated by Na+, K+, Ca²+ and Mg²+ but inhibited by EDTA, DNP and HgCI2. The enzyme was highly susceptible to heat, losing all its activity within thirty minutes of heating at 70 °C. IFE Journal of Science Vol. 9 (2) 2007 pp. 149-154