Hydrolysis of rat melanin-concentrating hormone by endopeptidase 24.11 (neutral endopeptidase).
Melanin-concentrating hormone (MCH) is a cyclic peptide which behaves as an antagonist of the pituitary melanotropic hormone alpha-melanocyte-stimulating hormone in fishes. Cloning of the rat MCH cDNA precursor recently revealed the presence of an additional putative peptide named NEI. The present work examined the susceptibility of these novel peptides to hydrolysis by various purified exo- and endo-peptidases including endopeptidases 24.11 (NEP), 24.15, 24.16, angiotensin-converting enzyme, leucine aminopeptidase and carboxypeptidase A. NEP attacked MCH at three sites of the molecule with an apparent affinity of about 12 microM and a kcat. of 4 min-1. The first site of cleavage was at Cys-7-Met-8, i.e. within the peptide loop formed by the internal disulphide bridge. NEP could therefore be considered as an MCH-inactivating peptidase since the degradation products generated are probably devoid of biological activity. In contrast, NEI neither inhibited the degradation of the NEP chromogenic substrate glutaryl-Phe-Ala-Phe-p-aminobenzoate nor was susceptible to proteolysis by NEP. Unlike NEP, angiotensin-converting enzyme, endopeptidase 24.15 and endopeptidase 24.16 appeared totally unable to cleave MCH, whereas the peptide was readily degraded by aminopeptidase M and carboxypeptidase A.
Checler
F
F
Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UPR 411), Sophia Antipolis, Valbonne, France.
Dauch
P
P
Barelli
H
H
Nahon
J L
JL
Vincent
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006868:Hydrolysis; D007028:Hypothalamic Hormones; D007700:Kinetics; D008543:Melanins / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D015260:Neprilysin / Q000378:metabolism*; D010455:Peptides / Q000302:isolation & purification / Q000378:metabolism; D010907:Pituitary Hormones / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D051381:Rats; D013379:Substrate Specificity
D007028:Hypothalamic Hormones; D008543:Melanins; D010455:Peptides; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; D015260:Neprilysin