Protease inhibitor controls prophenoloxidase activation in Manduca sexta

• Published in: FEBS letters 1986-11, Vol.208 (1), p.113-116
• Main Authors: Saul, Steven J., Sugumaran, Manickam
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Catalysis; Catechol Oxidase - antagonists & inhibitors; Catechol Oxidase - metabolism; Chromatography - methods; Endopeptidases - metabolism; Enzyme Activation; Enzyme Precursors - antagonists & inhibitors; Enzyme Precursors - metabolism; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hemolymph - analysis; Lepidoptera - enzymology; Manduca sexta; Moths - enzymology; Oxidoreductases; prophenoloxidase; Prophenoloxidase Enzyme activation Enzyme inhibitor Proteolysis Insect immunity (Manduca sexta); Protease Inhibitors - physiology; proteinase inhibitor; Serine Endopeptidases; Sphingidae
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(86)81543-5

Prophenoloxidase from the hemolymph of tobacco hornworm Manduca sexta can be activated by a specific activating enzyme found in the cuticle. Inhibition studies with benzamidine, diisopropyl phosphofluoridate and p-nitrophenyl- p′-guanidinobenzoate indicate that the activating enzyme is a trypsin-like serine protease. An endogenous protease inhibitor, isolated from the hemolymph of Manduca larvae, inhibits the prophenoloxidase activation mediated by this enzyme. These results indicate that the probable physiological role of endogenous protease inhibitor is to control the undesired activation of prophenoloxidase in the hemolymph.