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 (original) (raw)
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Brain Research, 1998
2q Angiotensin converting enzyme ACE is Zn metallopeptidase which plays an important role in blood pressure homeostasis in mammals and other vertebrates. Homologues of ACE involved in the biosynthesis of mammalian peptide hormones have also been identified in the insects, Musca domestica, Drosophila melanogaster and Haematobia irritans exigua. In the pursuit of the biological role of insect ACE, this work focused on the tissue and cellular distribution of ACE in several insect species. The localisation of ACE in the central nervous system and reproductive tissues from a number of insect species suggests that ACE is of physiological importance in these tissues. By means of an antiserum to housefly ACE, we found that ACE-like immunoreactivity was abundantly present in the neuropil areas of the brain of all insects investigated, suggesting a role for ACE in the metabolic inactivation of peptide neurotransmitters. Especially in the fleshfly, Neobellieria bullata neuropile staining is abundant. In the cockroach Leucophaea maderae, immunoreactive staining was abundant in the neuronal perikarya as well as in the neuropilar regions. Staining in neurosecretory cells was also observed in the brains of the lepidopteran species, Bombyx mori and Mamestra brassica. The localisation of ACE in neurosecretory cells is consistent with the role as a processing hormone, involved in the generation of active peptide hormones. ACE was found to be co-localised with peptides of the FXPRLamide family in M. brassica and in B. mori, suggesting a role for the biosynthesis of these hormones. Finally, we found ACE-like immunoreactivity in the testis of Locusta migratoria, N. bullata and Leptinotarsa decemlineata, providing additional evidence for its important role in insect reproduction. q 1998 Elsevier Science B.V.
Peptides, 1997
The presence in insect tissues of peptides with structural similarities to angiotensin I and to bradykinin, the two best known substrates of mammalian angiotensinconverting enzyme, has not been reported. As part of our study to identify potential substrates for insect angiotensin-converting enzyme, we have investigated the susceptibility of a number of known insect peptide hormones and neurotransmitters to hydrolysis by Musca domestica angiotensin-converting enzyme. Insect peptides belonging to the red pigment-concentrating hormone, leucokinin, locust tachykinin, and depolarizing peptide families were hydrolyzed by housefly angiotensin-converting enzyme, whereas proctolin and crustacean cardioactive peptide were not substrates. Cus-DP II, LK I, LK II, and Lom-TK I were all cleaved at the penultimate C-terminal peptide bond to release a dipeptide amide as a major fragment with K m values of 94 { 11, 634 { 81, and 296 { 35 mM for Cus-DP II, LK I, and Lom-TK I, respectively. The ability of insect angiotensin-converting enzyme to hydrolyze C-terminally amidated peptides in vitro might be of functional significance because the enzyme has been localized to neuropile regions of the insect brain and is present in the hemolymph of houseflies. ᭧ 1997 Elsevier Science Inc. Musca domestica Angiotensin-converting enzyme Neuropeptide metabolism Insect neuropeptides
Peptidyl dipeptidase activity in the haemolymph of insects
Biochemical Society Transactions, 1994
Developments in microanalysis methods and high performance liquid chromatography have resulted in the isolation and sequencing of a large number of peptide hormones from insects. This has led to an appreciation of the diversity of insect peptide structures and the large number of physiological processes (e.g lipid and carbohydrate metabolism, diuresis, development, behaviour and reproduction), which are regulated at some stage by peptides synthesized either in the central nervous system or in endocrine glands[ I]. Many of these peptide hormones are synthesized in specialized neurosecretory cells in the neural ganglia, from where they are transported along axonal processes to neurohaemal sites for release into the haemolymph. Once released into the circulation, peptides have a limited half life as they can be degraded by proteases and peptidases present in the
Biopolymers, 2007
Insect neuropeptides of the insect kinin class share a common C-terminal pentapeptide sequence F1X12X23W4G5-NH2 (X23 = P, S, A) and regulate such critical physiological processes as water balance and digestive enzyme release. Analogs of the insect kinin class, in which the critical residues of F1, P3, and W4 were replaced with β3-amino acid or their β2-homo-amino acid variants, have been synthesized by the solid phase peptide strategy. The resulting single- and double-replacement analogs were evaluated in an insect diuretic assay and enzyme digestion trials. Analogs modified in the core P3 position produce a potent and efficacious diuretic response that is not significantly different from that obtained with the endogenous achetakinin peptides. The analogs also demonstrate enhanced resistance to hydrolysis by ACE and NEP, endopeptidases that inactivate the natural insect neuropeptides. This paper describes the first instance of β-amino acids analogs of an arthropod peptide that demonstrate significant bioactivity and resistance to peptidase degradation. © 2006 Wiley Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88:76–82, 2007.This article was originally published online as an accepted preprint. The “Published Online”date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.
Biochemical Journal, 1994
Ala2,Leu5]Enkephalin was readily metabolized by membranes (40000 g pellet) prepared from heads of the housefly, Musca domestica, with Gly3-Phe4 being the major site of cleavage. This hydrolysis was only partially inhibited (40 %) by 10 ,uM phosphoramidon, an inhibitor of endopeptidase-24.11, but was almost totally abolished in the presence of a mixture of 10 ,uM phosphoramidon and 10 ,M captopril, a potent inhibitor of mammalian angiotensin-converting enzyme (ACE). An assay for ACE employing Bz-Gly-His-Leu as the substrate was used to confirm the presence of an ACE-like peptidyl dipeptidase activity in fly head membranes. The peptidase had a Km of 1.91 mM for Bz-Gly-His-Leu and a pH optimum of 8.2. The activity was inhibited by 100 ,uM EDTA and was greatly activated by ZnCl2 but not other bivalent metal ions. Captopril, lisinopril, fosinoprilat and enalaprilat, all selective inhibitors of mammalian