Applied Biochemistry and Microbiology (2013) 49, 419-425

R. Katoch and A. Jamwal (2013)
Characterization of alpha-amylase inhibitor from rice bean with inhibitory activity against midgut alpha-amylases from Spodoptera litura
Applied Biochemistry and Microbiology 49 (4), 419-425
Abstract: The alpha-amylase inhibitor (alpha-AI) activity varied from 7.529 to 10.766 (IU/g) in 13 rice bean with different genotypes. BRS-2 exhibited the highest alpha-AI activity (55.3%). Rice bean alpha-AI was purified to homogeneity by 80% ammonium sulfate precipitation, dialysis, ion exchange chromatography on DEAE-Sepharose and gel filtration through Superdex-75. Its homogeneity was confirmed by SDS-PAGE under reducing conditions showing a single band protein of molecular weight 25 kDa. The inhibitor was purified to 75.9 fold with final yield of 28.0% with specific activity of 660.2 IU. Inhibition studies carried out at pH from 2.2 to 9.0 revealed pH optimum at pH 6.9 (69.3%). The maximum alpha-AI activity was found at 37°C (68.8 %) and the lowest was revealed at 100°C (37.0%). Optimum inhibitory activity was expressed during pre-incubation of enzyme with inhibitor at pH 6.9 and 37°C. Isoelectric focusing of purified inhibitor showed a single band near pH 4.7. The first 6 amino acids in the N-terminus were recorded as Ala-Ser-Ser-Arg-Phe-Cys (ASSRFC). The purified inhibitor inhibited the alpha-amylase from the larval midgut of Spodoptera litura up to 86.6%. The alpha-amylase inhibitors are important seed storage proteins because of their potentiality for exploitation in pest control and crop defense against insect infestation. Their expression at high levels can confer resistance in transgenic legumes, which could be exploited for crop improvement.
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Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera litura