Some properties of partially purified alpha amylase from Rice (Oryza sativa)

Abstract

The present study was aimed at determining some properties of partially purified alpha amylase from rice (Oryza sativa). Different cultivars of rice were tested for alpha amylase production. The crude α-amylase was obtained by homogenization of day one germinated rice (cultivar ‘Election’) in sodium acetate buffer pH 4.0. After centrifugation, the crude enzyme was subjected to 20% (w/v) ammonia sulphate precipitation and dialysis, and its biochemical and kinetic properties were analyzed. After dialysis, the specific activity 1715.875 U/mg with purification fold of 3 and 60% recovery was obtained for the enzyme. The Km and Vmax were found to be 9 mg/ml and 178. µmol/min for rice starch, 5.150 mg/ml and 50.000 µmol/min for cassava starch, and 14.667 mg/ml and 111.111 µmol/min for maize starch, respectively. The specificity constant was found to be 13.888 min-1, 9.709 min-1 and 7.576 min-1 for rice, cassava and maize respectively. This shows that α-amylase has greater affinity for rice starch than the other starches used. The optimum pH and temperature were found to be 7.5 and 50 ºC respectively. The presence of metal ion such as Ca2+, Co2+, Fe3+, and Zn2+ activated α-amylase activity while Pb2+ and Mn2+ inhibited α-amylase activity. The results obtained from the present study indicated that Oryza sativa, is a good source of α-amylase for food industry, hence possess the properties for biotechnological applications.