Inhibition of Sunn pest, Eurygaster integriceps, α-amylases by α-amylase inhibitors (T-αAI) from Triticale
Insect Biochemistry & Molecular Biology Lab, Plant Protection Dep., Agricultural and Natural Resources Campus, University of Tehran, Karaj, Iran
Abstract
The effect of triticale α-amylases inhibitors on starch hydrolysis catalyzed by the Sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae) midgut amylases was examined. Biochemical studies showed that inhibitors from Triticale (a hybrid of wheat and rye) had inhibitiory effects on E. integriceps α‐amylases. The effects of the triticale α‐amylase inhibitor (T‐αAI) on α‐amylase of E. integriceps showed a dose dependent manner of inhibition, e.g. less inhibition of enzyme activity (around 10%) with a lower dose (0.25 mg protein) and high inhibition of enzyme activity (around 80%) when a high dose of inhibitor was used (1.5 mg protein). The enzyme kinetic studies using Michaelis-Menten and Lineweaver-Burk equations showed the Km remained constant (0.58%) but the maximum velocity (Vmax) decreased in the presence of a crude extract of Triticale inhibitors, indicating mixed inhibition. The temperature giving 50% inactivation of enzyme (T50) during a 30-min incubation at pH 7.0 was 73º C. The maximum inhibitory activity was achieved at 35º C and pH 5.0. Gel assays showed the meaningful inhibition of E. integriceps α‐amylases by various concentrations of Triticale inhibitors. Based on the data presented in this study, it could be said that the T‐αAI has good inhibitory activity on E. integriceps gut α‐amylase.
Keywords: Scutelleridae, mode of inhibition
Abbreviations: PPA, porcine pancreas α-amylase; T-αAI, triticale α-amylase inhibitor; Ki, Inhibitory (dissociation)
constant for the enxyme-inhibitor complex; K'i, dissociation constant for inhibitor from enzyme-substrate-inhibitor
complex; T50, The temperature giving 50% inactivation
Correspondence: a*mmehrabadi@ut.ac.ir, babandani@ut.ac.ir, cfsaadati@ut.ac.ir, *Corresponding author
Received: 8 May 2009 | Accepted: 23 June 2009 | Published: 13 October 2010
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 10, Number 179
Mehrabadi M, Bandani AR, Saadati F. 2010. Inhibition of Sunn pest, Eurygaster integriceps, α-amylases by α-amylase inhibitors (T-αAI) from Triticale. Journal of Insect Science 10:179, available online: insectscience.org/10.179
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