title: Role of proteases in extra-oral digestion of a predatory bug, Andrallus spinidens.
abstract: Roles of salivary proteases in the extra-oral digestion of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae) were studied by using 2% azocasein as a general substrate and specific protease substrates, as well as synthetic and endogenous inhibitors. It was found that salivary glands of A. spinidens have two anterior, two lateral, and two posterior lobes. Azocasein was used to measure the activity of general proteases in the salivary glands using different buffer solutions. The enzyme had the highest activity at pH 8. General protease activity was highest at 40 °C and was stable for 6-16 hours. The use of specific substrates showed that trypsin-like, chymotrypsin-like, aminopeptidase, and carboxypeptidase are the active proteases present in salivary glands, by the maximum activity of trypsin-like protease in addition to their optimal pH between 8-9. Ca(2+) and Mg(2+) increased proteolytic activity about 216%, while other ions decreased it. Specific inhibitors including SBTI, PMSF, TLCK, and TPCK significantly decreased enzyme activity, as well as the specific inhibitors of methalloproteases including phenanthroline, EGTA, and TTHA. Extracted endogenous trypsin inhibitors extracted from potential prey, Chilo suppressalis, Naranga aenescens, Pieris brassicae, Hyphantria cunea, and Ephestia kuhniella, had different effects on trypsin-like protease activity of A. spinidens salivary glands. With the exception of C. suppressalis, the endogenous inhibitors significantly decreased enzyme activity in A. spinidens.
authors.affiliation: Department of Plant Protection, College of Agriculture, University of Guilan-Rasht, Iran. arash.zibaee@gmx.com
authors.forename: Arash
authors.initials: A
authors.lastname: Zibaee
authors.forename: Hassan
authors.initials: H
authors.lastname: Hoda
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Fazeli-Dinan
mesh_terms: D000818:Animals; D002413:Cations, Divalent; D002414:Cations, Monovalent; D004063:Digestion; D005247:Feeding Behavior; D006430:Hemiptera / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D009036:Moths / Q000737:chemistry; D010447:Peptide Hydrolases / Q000378:metabolism*; D011235:Predatory Behavior; D011480:Protease Inhibitors / Q000302:isolation & purification; D012469:Salivary Glands / Q000033:anatomy & histology / Q000201:enzymology*; D013696:Temperature
chemical_list: D002413:Cations, Divalent; D002414:Cations, Monovalent; D011480:Protease Inhibitors; D010447:Peptide Hydrolases