Insect peptidyl-dipeptidase A [angiotensin I-converting enzyme (ACE)] is a soluble single-domain peptidyl-dipeptidase that has many properties in common with the C-domain of mammalian somatic ACE and with the single-domain mammalian germinal ACE. Mammalian somatic ACE is important in blood homoeostasis, but the role of ACE in insects is not known. Immunocytochemistry has been used to localize ACE in the neuroendocrine system of the locust, Locusta migratoria. Staining was observed in five groups of neurosecretory cells in the brain and suboesophageal ganglion, in the nervi corpori cardiaci, the storage part of the corpora cardiaca and in the nervi corpori allati. In three groups of neurosecretory cells, ACE co-localized with locustamyotropins, suggesting a possible role for the enzyme in the metabolism of these neuropeptides. We demonstrate in vitro a novel activity of ACE that removes pairs of basic amino acid residues from a locustamyotropin peptide extended at the C-terminus with either Gly-Lys-Arg or Gly-Arg-Arg, corresponding to a consensus recognition sequence for endoproteolysis of prohormone proteins by prohormone convertases. The low Km and high kcat values (Km 7.3 and 5.0 μM, kcat 226 and 207 s-1 for the hydrolysis of Phe-Ser-Pro-Arg-Leu-Gly-Lys-Arg and Phe-Ser-Pro-Arg-Leu-Gly-Arg-Arg, respectively) obtained for the hydrolysis of these two peptides by insect ACE means that these peptides, along with mammalian bradykinin, are the most favoured in vitro ACE substrates so far identified. The discovery of this in vitro prohormone-processing activity of insect ACE provides a possible explanation for the intracellular co-localization of the enzyme with locustamyotropin peptides, and provides evidence for a new role for ACE in the biosynthesis of peptide hormones and transmitters.
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February 1998
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Research Article|
February 15 1998
A novel peptide-processing activity of insect peptidyl-dipeptidase A (angiotensin I-converting enzyme): the hydrolysis of lysyl-arginine and arginyl-arginine from the C-terminus of an insect prohormone peptide
R. Elwyn ISAAC;
R. Elwyn ISAAC
1
*Department of Biology, University of Leeds, Leeds LS2 9JT, U.K.
1To whom correspondence should be addressed.
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Liliane SCHOOFS;
Liliane SCHOOFS
†Zoological Institute, Katholieke Universiteit Leuven, Naamsestraat 59, 3000 Leuven, Belgium
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A. Tracy WILLIAMS;
A. Tracy WILLIAMS
‡INSERM Unit 36, College de France, 3 d'Ulm, 75005 Paris, France
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Dirk VEELAERT;
Dirk VEELAERT
†Zoological Institute, Katholieke Universiteit Leuven, Naamsestraat 59, 3000 Leuven, Belgium
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Mohammed SAJID;
Mohammed SAJID
*Department of Biology, University of Leeds, Leeds LS2 9JT, U.K.
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Pierre CORVOL;
Pierre CORVOL
‡INSERM Unit 36, College de France, 3 d'Ulm, 75005 Paris, France
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David COATES
David COATES
*Department of Biology, University of Leeds, Leeds LS2 9JT, U.K.
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Publisher: Portland Press Ltd
Received:
July 18 1997
Accepted:
September 18 1997
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 330 (1): 61–65.
Article history
Received:
July 18 1997
Accepted:
September 18 1997
Citation
R. Elwyn ISAAC, Liliane SCHOOFS, A. Tracy WILLIAMS, Dirk VEELAERT, Mohammed SAJID, Pierre CORVOL, David COATES; A novel peptide-processing activity of insect peptidyl-dipeptidase A (angiotensin I-converting enzyme): the hydrolysis of lysyl-arginine and arginyl-arginine from the C-terminus of an insect prohormone peptide. Biochem J 15 February 1998; 330 (1): 61–65. doi: https://doi.org/10.1042/bj3300061
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