Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.37 (neutrophil elastase)
 4,078 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we have reported that some guanidino-substituted alpha- and beta-aryl enol lactones I and II behaved as selective, mechanism-based inhibitors of some trypsin-like proteases (Rai, R.; Katzenellenbogen, J.A. J. Med. Chem., submitted). In this study, we describe the synthesis and kinetic evaluation of some related, guanidino-substituted enol lactones having greater conformational mobility and affording additional hydrogen-bonding sites at the active site. The alpha-aryl-substituted lactones 1 and 2, which have greater conformational mobility in the guanidinoaryl linkage than I, selectively inhibited the trypsin-like enzymes, and they were relatively poor inactivators of alpha-chymotrypsin and human neutrophil elastase (HNE). The iodo enol lactone 2 permanently inactivated trypsin, urokinase, tissue plasminogen activator, and plasmin, showing exceptionally high specificity in its interaction with trypsin and urokinase. The selectivity pattern exhibited by the closely related, conformationally less mobile alpha-aryl-substituted iodo lactone Ib, which was previously shown to be a selective suicide substrate of urokinase and plasmin, provides an interesting comparison. The alpha-benzamido-substituted lactones 3 and 4, which afford an additional site for active-site hydrogen bonding, were found to be very potent alternate substrate inhibitors of trypsin and urokinase. In addition, the iodo lactone 4 permanently inactivated alpha-chymotrypsin. The importance of secondary interactions in increasing the specificities in the case of alpha-chymotrypsin is discussed.
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PMID:Effect of conformational mobility and hydrogen-bonding interactions on the selectivity of some guanidinoaryl-substituted mechanism-based inhibitors of trypsin-like serine proteases. 144 34

Procollagenase M(r) 85,000 (SDS-PAGE) was purified from buffy coat to homogeneity and represents a stable single polypeptide chain forming the entire proenzyme. The procollagenase can be activated by various proteinases, e.g. trypsin, chymotrypsin, cathepsin G, kallikrein and stromelysin and by different mercurial compounds. Proteolytic conversion of the latent enzyme to the active form by chymotrypsin is accompanied by a molecular weight reduction to an apparent M(r) 64,000. This active enzyme lacks the first 79 N-terminal residues. Activation by trypsin leads to a latent intermediate of apparent M(r) 70,000, lacking 48 N-terminal residues. The active enzyme is therefore generated upon prolonged incubation with trypsin by further cleavage of 22 N-terminal residues. Another latent intermediate form with apparent M(r) 69,000 is generated from the proenzyme upon incubation with leukocyte elastase by N-terminal cleavage of 53 or 64 residues, respectively. However, latent collagenase cannot be activated by plasmin. Activation by different mercurial compounds finally results in the formation of active collagenase with apparent M(r) 64,000. In contrast to the proenzyme, active collagenase can autolyse to give active M(r) 57,000 and 45,000 intermediates and two M(r) 28,000 fragments. Purification of latent leukocyte gelatinase yields three final products with apparent M(r) 98,000, 125,000 and 220,000 (SDS-PAGE; non reduced). Upon reduction, only the M(r) 98,000 form can be detected. The latent gelatinase can be activated in a similar manner as collagenase. Proteolytic activation by trypsin leads after N-terminal cleavage to an active gelatinase with sequence homology to leukocyte collagenase.
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PMID:Latent collagenase and gelatinase from human neutrophils and their activation. 148 34

The role of the antiproteases alpha 1-proteinase inhibitor (alpha 1PI) and mucus proteinase inhibitor (MPI) in human lung emphysema was investigated by measuring their amount and functional activity against trypsin, leukocyte elastase, and pancreatic elastase in the bronchoalveolar lavage fluid (BALF). In addition, leukocyte elastase was quantified in the lavage samples by measuring the concentration of the elastase-alpha 1PI-complex. The study population consisted of 38 patients (5 nonsmokers, 8 former smokers, 25 smokers) with acquired emphysema (i.e., emphysema which is not caused by alpha 1PI deficiency), and 44 individuals (16 nonsmokers, 8 former smokers, 20 smokers) without emphysema. No differences were found between patients with and without emphysema in the activities of alpha 1PI and MPI, or in the concentration of alpha 1PI. The concentration of MPI was significantly higher in the BALF of patients with emphysema than in that of patients without emphysema (p = 0.025). A significantly higher concentration of elastase-alpha 1PI complex was found in patients with emphysema than in those without emphysema (p = 0.041). This finding could reflect the higher proteinase burden to which patients with emphysema are exposed. The increase of MPI in lavage fluid of patients with emphysema seems to be the result of increased production in emphysematous lungs. However, it remains unclear why patients develop emphysema while showing an increased content of MPI.
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PMID:Alpha 1-proteinase inhibitor and mucus proteinase inhibitor in human lung emphysema. 152 Oct 41

In the nanomolar enzyme and inhibitor concentration range, 1 mol of mucus proteinase inhibitor (MPI) inhibits 1 mol of neutrophil elastase, cathepsin G, trypsin, and chymotrypsin. In the micromolar concentration range, the enzyme:inhibitor binding stoichiometry is still 1:1 for elastase but shifts to 2:1 for the three other proteinases. These data could be confirmed by three nonenzymatic methods: (i) fluorescence anisotropy measurements of mixtures of proteinases with 5-dimethylaminonaphthalene-1-sulfonylated or fluoresceinylated MPI, (ii) absorption spectrocospy of fluorescein-MPI-proteinase complexes isolated by gel filtration, (iii) analytical ultracentrifugation which showed that the molecular mass of the MPI-chymotrypsin complex is 56 kDa, whereas that of the MPI-elastase complex is 39 kDa. The binary MPI-elastase complex is unable to inhibit trypsin or cathepsin G. On the other hand, 1 mol of elastase displaces 2 mol of trypsin or cathepsin G from their ternary complexes with MPI.
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PMID:The proteinase: mucus proteinase inhibitor binding stoichiometry. 153 27

Protease injury of the bronchial epithelium may play an important role in the pathogenesis of many airway diseases including asthma and chronic bronchitis. We hypothesized that neutrophil elastase can cause significant injury to the bronchial epithelium leading to detachment of bronchial epithelial cells. This detachment might be prevented if elastase is released into the airway lumen and the bronchial epithelium forms a barrier preventing access to the basal attachment sites. To assess this, the detachment of bronchial epithelial cells by elastase from extracellular matrix was measured. An increase in the resistance to detachment with time in culture was observed. The resistance to detachment was confirmed in bronchial epithelial cells, which were grown to electrically resistant monolayers on millipore filters and exposed to trypsin and elastase applied to both the apical and basal surfaces. Significantly greater detachment occurred when the proteases were applied at the basal surface versus the apical surface. Injury to the bronchial epithelium may enhance the proteolytic effect on the epithelium by disrupting epithelial barrier function. This was tested by exposing bronchial epithelial cell cultures to cigarette smoke extract before exposure to trypsin and elastase. The detachment of the bronchial epithelial cells exposed on the apical surface was increased greatly after smoke exposure. These data suggest that an intact bronchial epithelium can act as a barrier against proteolytic injury. Such a mechanism might protect the airway epithelium during intraluminal inflammation, and, if defective, might potentiate cigarette smoke-induced airway injury.
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PMID:Observations of development of resistance to detachment of cultured bovine bronchial epithelial cells in response to protease treatment. 155 Jun 86

Formation of the covalently stabilized alpha 1-antitrypsin (alpha 1-AT)-neutrophil elastase complex, the archetype of serpin-enzyme complexes, results in a structurally rearranged alpha 1-AT molecule that possesses chemo-attractant activities, mediates an increase in synthesis of alpha 1-AT by mononuclear phagocytes and hepatocytes, and is more rapidly cleared from the circulation than is the native alpha 1-AT molecule. We have recently identified an abundant, high affinity cell surface receptor on human hepatoma HepG2 cells and human monocytes that binds alpha 1-AT-elastase complexes, mediates endocytosis and lysosomal degradation of alpha 1-AT-elastase complexes, and induces an increase in synthesis of alpha 1-AT. We have referred to this receptor as the serpin-enzyme complex, or SEC, receptor because it also recognizes complexes of serpins antithrombin III, alpha 1-antichymotrypsin, and C1 inhibitor with their cognate enzymes. In the current study, we show that a pentapeptide domain in the carboxyl terminal fragment of alpha 1-AT (amino acids 370-374, FVFLM) is sufficient for binding to the SEC receptor. A synthetic analog of this pentapeptide (peptide 105C, FVYLI) blocks binding and internalization of alpha 1-AT-125I-trypsin complexes by HepG2 cells. 125I-Peptide 105C binds specifically and saturably to HepG2 cells, and its binding is blocked by alpha 1-AT-trypsin or alpha 1-AT-elastase complexes. Alterations of this sequence introduced into synthetic peptides (mutations, deletions, or scrambling) demonstrate that binding of the pentapeptide domain is sequence-specific. Comparisons with the sequences of other serpins in the corresponding region indicate that this pentapeptide neodomain is highly conserved.
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PMID:The SEC receptor recognizes a pentapeptide neodomain of alpha 1-antitrypsin-protease complexes. 164 29

In vivo most extracellular iron is bound to transferrin or lactoferrin in such a way as to be unable to catalyze the formation of hydroxyl radical from superoxide (.O2-) and hydrogen peroxide (H2O2). At sites of Pseudomonas aeruginosa infection bacterial and neutrophil products could possibly modify transferrin and/or lactoferrin forming catalytic iron complexes. To examine this possibility, diferrictransferrin and diferriclactoferrin which had been incubated with pseudomonas elastase, pseudomonas alkaline protease, human neutrophil elastase, trypsin, or the myeloperoxidase product HOCl were added to a hypoxanthine/xanthine oxidase .O2-/H2O2 generating system. Hydroxyl radical formation was only detected with pseudomonas elastase treated diferrictransferrin and, to a much lesser extent, diferriclactoferrin. This effect was enhanced by the combination of pseudomonas elastase with other proteases, most prominently neutrophil elastase. Addition of pseudomonas elastase-treated diferrictransferrin to stimulated neutrophils also resulted in hydroxyl radical generation. Incubation of pseudomonas elastase with transferrin which had been selectively iron loaded at either the NH2- or COOH-terminal binding site yielded iron chelates with similar efficacy for hydroxyl radical catalysis. Pseudomonas elastase and HOCl treatment also decreased the ability of apotransferrin to inhibit hydroxyl radical formation by a Fe-NTA supplemented hypoxanthine/xanthine oxidase system. However, apotransferrin could be protected from the effects of HOCl if bicarbonate anion was present during the incubation. Apolactoferrin inhibition of hydroxyl radical generation was unaffected by any of the four proteases or HOCl. Alteration of transferrin by enzymes and oxidants present at sites of pseudomonas and other bacterial infections may increase the potential for local hydroxyl radical generation thereby contributing to tissue injury.
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PMID:Pseudomonas and neutrophil products modify transferrin and lactoferrin to create conditions that favor hydroxyl radical formation. 165 25

In recent years, many studies have suggested a direct role for alpha 2-macroglobulin (alpha 2M), a plasma proteinase inhibitor, in growth factor regulation. When coincubated in the presence of either trypsin, pancreatic elastase, human neutrophil elastase, or plasmin, 125I-insulin rapidly formed a complex with alpha 2M which was greater than 80% covalent. The covalent binding was stable to reduction but abolished by competition with beta-aminopropionitrile. Neither native alpha 2M nor alpha 2M pretreated with proteinase or methylamine incorporated 125I-insulin. Experiments utilizing alpha 2M cross-linked with cis-dichlorodiammineplatinum(II) indicated that 125I-insulin must be present during alpha 2M conformational change to covalently bind. A maximum stoichiometry of 4 mol of insulin bound per mole of alpha 2M and the short half-life of the alpha 2M intermediate capable of covalent incorporation were consistent with thiol ester involvement. Protein sequence analysis of unlabeled insulin-alpha 2M complexes, together with results of beta-aminopropionitrile competition, confirmed that insulin incorporation occurs via the same gamma-glutamyl amide linkage responsible for covalent proteinase and methylamine binding to alpha 2M. Although intact insulin apparently incorporated through its sole lysine residue on the B chain, we found that isolated A chain also bound covalently to alpha 2M. Phenyl isothiocyanate derivatization of the N-terminus had no effect on A-chain binding, supporting the possibility of heretofore unreported gamma-glutamyl ester linkages to alpha 2M.
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PMID:Mechanism of insulin incorporation into alpha 2-macroglobulin: implications for the study of peptide and growth factor binding. 170 57

Positive affinity chromatography on heparin-Sepharose has proved a most crucial step in the purification of pregnancy-associated plasma protein A (PAPP-A). In this chromatographic procedure, PAPP-A was purified almost 500-fold from term pregnancy serum. Further purification was achieved by gel filtration and negative immunoaffinity chromatography. Both PAPP-A and free heparin inhibited granulocyte elastase (HGE) activity. Whereas free heparin inhibited only in hypotonic buffers, PAPP-A inhibited HGE in hypertonic buffers also. However, PAPP-A did not inhibit other proteases (trypsin, chymotrypsin, plasmin, fibroblast collagenase) or proteolytic cascades (complement activation). Since heparin was not detected in the purified PAPP-A, the inhibition of HGE was not due to desorbed or leeched heparin ligand.
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PMID:Pregnancy-associated plasma protein A interaction with heparin: a critical appraisal. 172 Oct 35

SR 26831 ([[5-(2-chloro-benzyl-2-(terbutyloxycarbonyl)]-4,5,6,7- tetrahydrothieno(3,2-c)pyridine]N-oxide) is the first member of a new class of human leukocyte elastase inhibitors. SR 26831 inhibited in a dose-dependent manner elastases from human leukocytes or pancreas with IC50 values of 80 +/- 2.6 nM and 4.8 +/- 0.12 microM, respectively. Steady-state studies revealed that SR 26831 behaved like a noncompetitive, irreversible inhibitor of both types of enzymes. SR 26831 inhibited in a dose-dependent manner degradation of [3H]elastin and [3H]collagens (types I and IV) by human leukocyte elastase (IC50 values were between 1.2 and 1.8 microM). In this respect, SR 26831 was 3- to 20-fold more active than alpha-1-antitrypsin. SR 26831 was also highly selective for elastases inasmuch as it did not inhibit pepsin, collagenase, trypsin, alpha-chymotrypsin, factor Xa, plasmin, kallikrein, cathepsins B, C, D and G and thrombin. In the rabbit, SR 26831 was cleared rapidly from blood after i.v. injection, but affected intracellular leukocyte elastase activity shortly after either i.v. or p.o. administration. In the rat, i.v. or p.o. administration of SR 26831 prevented in a dose-dependent manner acute lung injury induced by intratracheal instillation of human leukocyte elastase. SR 26831 (1 mg/kg) was still efficient when it was administered 90 min before elastase instillation and was also able to limit further hemorrhage development in response to elastase, after it had begun. SR 26831 may therefore be of therapeutic value in the treatment of diseases such as rheumatoid arthritis or pulmonary emphysema thought to be due to the destructive action of leukocyte elastase.
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PMID:Biochemical and pharmacological activities of SR 26831, a potent and selective elastase inhibitor. 173 26


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