title: Identification of two zinc metalloendopeptidases in alveolar macrophages of rats, guinea pigs, and human beings.
abstract: Neutral endopeptidases EC 3.4.24.11 and EC 3.4.24.15, widely distributed zinc metalloendopeptidases, degrade a number of biologically active peptides including substance P, bradykinin, neurotensin, and luteinizing hormone-releasing hormone. In this study we measured EC 3.4.24.11 and EC 3.4.24.15 activity in alveolar macrophages, key inflammatory cells in the lung that produce and respond to a large number of bioactive substances including chemotactic peptides, with the substrates glutaryl-ala-ala-phe-2-naphthylamide and tertiary butoxycarbonyl-phe-ala-ala-phe-paraaminobenzoate, respectively. We found that specific activity of EC 3.4.24.15, defined as activity inhibited with N-[(1RS)-carboxy-3-phenylpropyl]-ala-ala-phe-paraaminobenzoate+ ++, was significantly higher (p < 0.001) in cells from Sprague-Dawley rats (485 +/- 123 nmol/mg protein.hr) than in cells from Hartley guinea pigs (138 +/- 94 nmol/mg protein.hr), healthy human male smokers (121 +/- 73 nmol/mg protein.hr) and healthy human male nonsmokers (94 +/- 12). In contrast, activity of EC 3.4.24.11, defined as activity inhibited with N-[(1RS)-carboxy-3-phenylpropyl]-phe-paraaminobenzoate, was significantly higher (p < 0.001) in cells from human smokers (689 +/- 167 nmol/mg protein.hr) and nonsmokers (762 +/- 136 nmol/mg protein.hr) than in cells from rats (52 +/- 12 nmol/mg protein.hr) and guinea pigs (34 +/- 14 nmol/mg protein.hr). An additional activity in alveolar macrophages toward tertiary butorycarbonyl-phe-ala-ala-phe-paraaminobenzoate was inhibited with L-3-carboxy-trans-2,3-epoxypropionyl-leucylamido-(4-guanido) butane, a specific inhibitor of cysteine proteinases, a finding of interest because in general enzymes in this class show little activity at neutral pH.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, Bronx Veterans Affairs Hospital, NY 10468.
authors.forename: M
authors.initials: M
authors.lastname: Lesser
authors.forename: K
authors.initials: K
authors.lastname: Fung
authors.forename: H S
authors.initials: HS
authors.lastname: Choi
authors.forename: O H
authors.initials: OH
authors.lastname: Yoo
authors.forename: C
authors.initials: C
authors.lastname: Cardozo
mesh_terms: D010129:4-Aminobenzoic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D006168:Guinea Pigs; D006801:Humans; D016676:Macrophages, Alveolar / Q000201:enzymology*; D008297:Male; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008969:Molecular Sequence Data; D015260:Neprilysin / Q000037:antagonists & inhibitors / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012907:Smoking / Q000378:metabolism; D013045:Species Specificity; D015032:Zinc; D062366:para-Aminobenzoates
chemical_list: D009842:Oligopeptides; D062366:para-Aminobenzoates; C064939:N-(1-carboxy-3-phenylpropyl)-alanyl-alanyl-phenylalanine-4-aminobenzoate; C077403:N-(1-carboxy-3-phenylpropyl)phenylalanine-4-aminobenzoate; D010649:Phenylalanine; D008666:Metalloendopeptidases; D015260:Neprilysin; C022510:thimet oligopeptidase; D015032:Zinc; D010129:4-Aminobenzoic Acid