title: Characterisation and inhibition studies of Helicoverpa armigera (Hübner) gut α-amylase.
abstract: BACKGROUND
  The survival of a devastating pest, Helicoverpa armigera, is mainly dependent on the availability of α-amylase. Therefore, characterising H. armigera α-amylase and targeting it with effective inhibitors could aid in reducing its damaging effects.
  
  
  RESULTS
  H. armigera gut possessed four isozymes of α-amylase. The molecular weight of the major purified isozyme ranged from 79 to 81 kDa. The purified enzyme was identified to be α-amylase on the basis of products formed from starch. The optimum pH and temperature were 10.0 and 50 °C respectively. The activation energy was 5.7 kcal mol(-1) . The enzyme showed high activity with starch and amylopectin, whereas dextrins were poor substrates. The Michaelis constant Km with starch, amylose and amylopectin was 0.45, 1.23 and 0.11 mg mL(-1) respectively. ZnSO4 , FeSO4 , CuSO4 , citric acid, oxalic acid and salicylic acid were potent inhibitors. ZnSO4 , salicylic acid and pigeonpea α-amylase inhibitor (∼21.0 kDa) acted primarily as competitive inhibitors, FeSO4 and citric acid displayed mainly anticompetitive behaviour, while CuSO4 and oxalic acid behaved mainly as non-competitive inhibitors.
  
  
  CONCLUSIONS
  The identification of effective ecofriendly inhibitors could help in managing H. armigera infestation. © 2014 Society of Chemical Industry.
authors.affiliation: Department of Biochemistry, Punjab Agricultural University, Ludhiana, India.
authors.forename: Rimaljeet
authors.initials: R
authors.lastname: Kaur
authors.affiliation: Department of Biochemistry, Punjab Agricultural University, Ludhiana, India.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Gupta
authors.affiliation: Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, India.
authors.forename: Gaurav K
authors.initials: GK
authors.lastname: Taggar
mesh_terms: D000818:Animals; D041981:Gastrointestinal Tract / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000201:enzymology; D009036:Moths / Q000201:enzymology*; D013696:Temperature; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000737:chemistry*
chemical_list: D000516:alpha-Amylases
keywords: Helicoverpa armigera; biochemical characterisation; inhibition kinetics; pigeonpea α-amylase inhibitor; substrate specificity; α-amylase