Degradation of Dip-allatostatins by hemolymph from the cockroach, Diploptera punctata.
Incubation of Dip-AST 7 (APSGAQRLYGFGLa) or Dip-AST 9 (GDGRLYAFGLa) (5 microM) with hemolymph for 30 min results in cleavage by a putative endopeptidase, yielding the C-terminal hexapeptide. This metabolic product is subsequently cleaved by an amastatin-sensitive aminopeptidase to yield the the C-terminal pentapeptide, as treatment with the competitive aminoexopeptidase inhibitor, amastatin, results in a significant accumulation of the C-terminal hexapeptide. Interestingly, Dip-AST 5 (DRLYSFGLa) (6 microM), which in common with Dip-AST 7 and 9 possesses Arg-Leu-Tyr, is not rapidly cleaved. However, [3H-Tyr]Dip-AST 5 at physiological concentrations (4 nM), appears to be cleaved by the same enzymes that cleave Dip-AST 7 and 9, albeit at a reduced rate. Incubation of other members of the Dip-allatostatin family with hemolymph also results in cleavage of the peptides, suggesting that there are a variety of endo- and/or exopeptidases present in the hemolymph of D. punctata.
Garside
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Department of Zoology, University of Toronto, ON, Canada.
Hayes
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Tobe
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D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003058:Cockroaches / Q000201:enzymology*; D010450:Endopeptidases / Q000378:metabolism; D020689:Exopeptidases; D006458:Hemolymph / Q000201:enzymology*; D006727:Hormone Antagonists / Q000378:metabolism; D007700:Kinetics; D009479:Neuropeptides / Q000737:chemistry / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology
D006727:Hormone Antagonists; D009479:Neuropeptides; D009842:Oligopeptides; D011480:Protease Inhibitors; C076523:allatostatin; D010450:Endopeptidases; D020689:Exopeptidases; D010447:Peptide Hydrolases