title: A cuticle-degrading proteinase from the moulting fluid of the tobacco hornworm, Manduca sexta.
abstract: Moulting fluid of pharate adult tobacco hornworm moths, Manduca sexta, contains a novel cuticle-degrading proteinase, designated as MFP-1. The enzyme has been purified using heparin affinity chromatography and partially characterized. Before purification MFP-1 is associated with a large complex having an apparent native molecular mass > 669 kDa. After purification MFP-1 has a molecular mass of 41 kDa. The pI of the enzyme is 5.54. MFP-1 can be classified as generally trypsin-like on the basis of its substrate specificity and inhibition by soybean trypsin inhibitor. The enzyme's preferred substrate, Tos-Gly-Pro-Arg-pNA, its inhibition by hirudin, and its affinity for heparin, all indicate that MFP-1 has some characteristics in common with the vertebrate blood-clotting enzyme thrombin. MFP-1 is probably a serine protease, since it is inhibited by both DFP and PMSF (specific inhibitors of serine proteinases). However, the enzyme was also inhibited by a number of agents that affect cysteine proteinases. Purified MFP-1 degrades Manduca cuticle in vitro. We suggest that the enzyme may act as the first step in the degradation of the cuticle during the moulting process.
authors.affiliation: School of Biological Sciences, University of Bath, England.
authors.forename: R I
authors.initials: RI
authors.lastname: Samuels
authors.forename: A K
authors.initials: AK
authors.lastname: Charnley
authors.forename: S E
authors.initials: SE
authors.lastname: Reynolds
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009036:Moths / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D011480:Protease Inhibitors; D010450:Endopeptidases; C082691:moulting fluid protease 1