Proteomic and Characterization of α-amylase Inhibitor from Mungbean (Vigna radiate)

Abstract

Callosobruchus maculatus, the insect pest, causes damaging to stored mungbean seeds leading to economical losses. For this reason the use of α-amylase inhibitors to interfere the pest digestion process has been an interesting alternative as a biocontrolling agent. The studies of gamma irradiated mungbean mutant, M5-16, demonstrated that α-amylase inhibitor from the mutant line was more inhibitory effective on C. maculatus α-amylase than its wild type, KPS1. To investigate this mechanism, both proteomics and biochemical characterization were employed. The α-amylase inhibitor from mungbean seed, M5-16, was purified in a two-step procedure involving ammonium sulfate precipitation and gel filtration chromatography using a sephadex G-100 column. This α-amylase inhibitor existed as a monomer and had a molecular weight of 27 kDa. Moreover, It was very interesting that α-amylase inhibitor from the mungbean seed inhibited C. maculatus α-amylase but did not inhibit human salivary α-amylase. 2D gel electrophoresis suggested that the gamma-induced mutant line has decreased expression of α-amylase inhibitor and other proteins comparing with its wild type.