Turkish Journal of Agriculture and Forestry




Midgut hydrolytic enzymes of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) were identified and partially characterized. K_m, V_{max}, optimum pH, and specific activity were determined for proteolytic enzymes and \alpha-amylases. All hydrolytic enzyme activity had an optimum pH value in the alkaline pH range. We observed major serine protease activity, together with minor cysteine-like activity, the former being significantly inhibited by soybean trypsin inhibitor (SBTI) and aprotinin. Moreover, different degrees of inhibition were observed with synthetic protease inhibitors. Electrophoretic methods revealed 3 isozymes of \alpha-amylases, of which 2 had higher molecular weight and were more active than the other. Inhibition of amylolytic activity was observed with wheat \alpha-amylase inhibitor (WAAI), whereas partially purified maize, chickpea, and bean seed crude extracts did not exhibit inhibitory activity toward \alpha-amylases. To the best of our knowledge this is the first report on the properties of \alpha-amylases from Helicoverpa armigera and the effects of several plant-originated a-amylase inhibitors on them.


Helicoverpa armigera, protease, protease inhibitors, α-amylase, \alpha-amylase inhibitors

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