α-Amylase Inhibitors from Some Cassia Species and Their Interaction with α-Amylase Potential for Crop Protection

Abstract

α-Amylase inhibitor proteins have inculcated a considerable attention over the past few years on account of their potential effect on the crop pest. Their importance in natural defense are not kept untouched with the routine gene manipulation techniques, where genes coding for these proteins have been expressed in transgenic seeds to create resistance toward storage pests. Cassia tora, Cassia occidentalis, Cassia floribunda and Crotalaria albida were analysed for α-amylase inhibitor activity. The α-amylase inhibitor from seeds of screened cultivar Cassia occidentalis, showing maximum inhibitory activity was purified using ammonium sulfate precipitation, gel filtration chromatography (Sephacryl S-200) and ion exchange chromatography (DEAE-Sephadex A-50). The inhibitor was found to be heat stable and retained its 94 % activity in Cassia tora at 70°C. The inhibitor was purified to homogeneity with 752.79 fold purification and 22.77 % recovery. Purified inhibitors consisted of subunits less than 200 KDa as determined by SDS-PAGE. After purification steps maximum specific activity has been observed in Cassia occidentalis which was 160.00 units/mg protein. After Cassia occidentalis, Cassia floribunda showed the specific activity which was 16.08 units/mg protein.