Abstract

• α-Amylases (1,4-α-D-glucan-glucanohydrolase EC 3.2.1.1) are found in human, several bacteria, yeast, fungi and seeds. This paper deals with the extraction of α-amylase from developing seeds of white kidney bean and studies on its kinetic properties. α-Amylase was extracted from immature white kidney bean (Phaseolus vulgaris L.) seeds by ammonium sulphate fractionation (20-60 %) and purified by gel filtration chromatography. The specific activity of purified α-amylase was 1.20 unit per mg of protein. The purity of enzyme was confirmed by non SDS-PAGE as a single band. The molecular weight of purified α-amylase was determined as 56.23 kDa. The optimum temperature and optimum pH for the α-amylase were 50˚C and 5.6, respectively. Kinetic parameters such as Michaelis-Menten constant Km and maximum velocity Vmax were 0.1267 x10-2 g mL-1 and 1.64 x10-5 M min-1 determined from a double reciprocal plot. Km and Vmaxvalues determined by other plots were also found to be comparable.