Identification and Characterization of α-Amylase from Yemeni Bean (Dolichos Lablab L.) Seeds

The α-amylase from local Yemeni bean (Dolichos Lablab) seeds was partially purified by conventional methods of protein purification such as pH and thermal precipitation, ammonium sulphate fractionation and ion-exchange chromatography on DEAE-Cellulose. Native Polyacrylamide Electrophoresis revealed that cashed á-amylase had isoform AmyI and AmyII. The enzyme AmyII showed the following characteristics: optimum pH 7.0, optimum temperature, Km value for hydrolyzing starch was 1.25 mg. The affinity between substrate and enzyme was detected only for glycogen and starch compared with other carbohydrates tested, where glycogen had more affinity than starch. Enzyme activity was stimulated by Ca2+, Ni2+ and Cd2+ , inhibited by Zn2+ and Hg2+. In conclusion, this á-amylase from Yemeni seeds have interesting characteristics such as low km value, neutral pH optimum, high optimum temperature, high affinity toward starch and glycogen and activation by some metal as calcium. Therefore, these meet the prerequisites need for food industry.