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

Abstract

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