Identification and characterization of hydrolytic enzymes from the midgut of the cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae)


Ozgur E., Yucel M., ÖKTEM H. A.

TURKISH JOURNAL OF AGRICULTURE AND FORESTRY, vol.33, no.3, pp.285-294, 2009 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 33 Issue: 3
  • Publication Date: 2009
  • Doi Number: 10.3906/tar-0802-5
  • Title of Journal : TURKISH JOURNAL OF AGRICULTURE AND FORESTRY
  • Page Numbers: pp.285-294
  • Keywords: Helicoverpa armigera, protease, protease inhibitors, alpha-amylase, alpha-amylase inhibitors, ALPHA-AMYLASE INHIBITOR, INSECT PEST, PROTEINASE-INHIBITORS, PROTEASE ACTIVITIES, GENE-EXPRESSION, LARVAL MIDGUT, CDNA CLONING, IN-VITRO, RESISTANCE, CARBOXYPEPTIDASE

Abstract

Midgut hydrolytic enzymes of Helicoverpa armigera Hubner (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 alpha-amylase inhibitors on them.