Identification and characterization of hydrolytic enzymes from the midgut of Sunn Pest of wheat (Eurygaster integriceps)


Ogur E., YÜCEL M., ÖKTEM H. A.

INTERNATIONAL JOURNAL OF PEST MANAGEMENT, vol.55, no.4, pp.359-364, 2009 (SCI-Expanded) identifier identifier

Abstract

To help in the development of Sunn Pest-resistant transgenic plants employing protease or alpha-amylase inhibitors, midgut hydrolytic enzymes of Sunn Pest (Eurygaster integriceps, Put.) (Heteroptera: Scutelleridae) were identified and characterized biochemically. We observed levels of very low proteolytic activity of trypsin (3 nmoles/min/mg), elastase (0.66 nmoles/min/mg) and leucine aminopeptidase-like (14.4 nmoles/min/mg) proteases, but no chymotrypsin and papain-like activity. Proteolytic activities were insensitive to inhibition by soybean trypsin inhibitor (SBTI) and aprotinin, but were inhibited to varying degrees (40-100%) by the synthetic protease inhibitors PMSF, TPCK, CdCl2 and CuCl2. Compared to proteolytic activity, significantly higher amylolytic activity (4.45 mmoles/min/mg) was observed. Alpha-amylase activity was found to be resistant to inhibition by bean and chickpea alpha-amylase inhibitors, and only slightly inhibited by wheat (36.9 +/- 1.8%) and maize (40.2 +/- 2.8) alpha-amylase inhibitors. Here, we report on the biochemical properties of digestive enzymes from Sunn Pest midgut, and their inhibition patterns by several synthetic and natural hydrolytic enzyme inhibitors.