Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Various biochemical events taking place during pulmonary inflammation were examined in the bronchoalveolar lavage (BAL) fluids from patients with acute respiratory distress syndrome (ARDS) and in experimental animal models. In patients with ARDS, active neutrophil elastase was found in the BAL fluids. In these fluids, inactivation of the major elastase inhibitor alpha 1-protease inhibitor (alpha 1-PI) occurred. This was caused by oxidation of a methionine residue at the active site of the alpha 1-PI, and offered indirect evidence of oxidation occurring in the inflamed pulmonary tissues. Studies with experimental animals have been initiated to gain understanding of the relative roles of proteases, oxidants, arachidonate metabolites, complement and contact system components, and other mediators in the pathogenesis of pulmonary inflammation. Intrabronchial instillation of glucose oxidase/glucose to produce oxidants or formylated norleucylleucylphenylalanine or phorbol myristate acetate as leukocytic stimuli induced severe acute pulmonary injury in New Zealand white rabbits and rhesus monkeys. The injury was accompanied by leukocytic protease (acid cathepsins) release in rabbit lungs and oxidant formation, and could be inhibited by neutrophil depletion. Oxidant formation was demonstrated by the inactivation of catalase by 3-amino-1,2,4-triazole in the presence of H2O2, a drop in intracellular glutathione levels, and in the rhesus monkey by inactivation of alpha 1-PI.
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PMID:Biochemical factors in pulmonary inflammatory disease. 638 73

Cleavage of C3 by purified leukocyte enzymes and crude extracts of human polymorphonuclear leukocyte (PMN) granules has been reported. We demonstrate that viable PMN mediate the cleavage of erythrocyte-bound C3b and C3bi via cell-associated proteases. Greater than 50% of 125IC3(x) was released from EAC43bix during a 5-min incubation with viable PMN at 37 degrees C. More than a 30-min incubation was required for substantial release from EAC43bx. Culture fluids from PMN suspensions had limited cleaving ability; cleavage of cell-bound C3bx and C3bix was only partially reduced when PMN were preincubated with high levels of soluble C3 which completely blocked EAC43b rosettes. Thus, cell-to-cell contact between opsonized erythrocytes and viable PMN with surface-associated proteases are responsible for cleavage of these opsonic sites. The effect of defined protease inhibitors on PMN cleaving activity as well as on purified leukocyte elastase was examined. Phenylmethylsulfonyl fluoride (PMSF) and the leukocyte elastase inhibitor, methoxy-succinate-alanine-alanine-valine-chloromethyl ketone (MeO) each inhibited cleavage of C3b by 90% and C3bi by 60%. In contrast, the cathepsin-G inhibitor, benzyloxy-carbonyl-glycine-leucine-phenylalanine-chloromethyl ketone (Z) inhibited C3b and C3bi cleavage by less than 20 and less than 5%, respectively. Ethylenediaminetetra-acetate (EDTA), which had a minimal effect on soluble leukocyte elastase, also inhibited PMN-related release. Thus, elastase appeared to be the principle but not the only enzyme responsible for cleavage of C3b and C3bi. PMSF and MeO had a minimal effect on the activity of purified C3bINA (Factor I); and PMN-mediated release of C3b fragments was not inhibited by anti-Factor I and anti-beta 1H (Factor H) IgG and Fab. Thus, these control proteins are not involved in the PMN-mediated cleavage under study. PMN-mediated cleavage of C3b was also inhibited when PMSF- and MeO-treated PMN were washed to remove the fluid phase phase protease inhibitor before adding EAC43b. This suggests that proteases localized in the PMN membrane, prior to the adherence of EAC43b, are responsible for C3b cleavage. Normal human serum was effective in blocking PMN-mediated release activity, while serum from alpha 1 antitrypsin-deficient patients was minimally effective. This suggests a mechanism for the in vivo regulation of PMN-mediated release of C3b and C3bi from opsonized particles by the natural plasma protease inhibitors.
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PMID:Cleavage of membrane-bound C3b and C3bi by viable human neutrophils (PMN). 660 72

Cigarette smoking is the major risk factor for the development of pulmonary emphysema, a disorder that may result from an imbalance between the elastase and antielastase levels in the lungs. Decreased functional alpha 1-protease inhibitor, an inhibitor of neutrophil elastase, might render smokers susceptible to elastase-catalyzed destruction of pulmonary elastic fibers and the development of emphysema. Binding and inactivation of isotopically labeled porcine pancreatic elastase and human neutrophil elastase by alpha 1-protease inhibitor were measured in fluid obtained by bronchoalveolar lavage of volunteers. The inhibition of elastase-catalyzed solubilization of elastin and a tripeptide substrate were also determined. The mean level of functional alpha 1-protease inhibitor in the bronchoalveolar lavage fluid of smokers was found to be equal to or greater than that of nonsmokers, contradicting reports by other investigators. Increased elastase derived from pulmonary neutrophils, rather than decreased functional alpha 1-protease inhibitor, appears to be the main factor in the genesis of emphysema in smokers.
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PMID:Functional alpha 1-protease inhibitor in the lower respiratory tract of cigarette smokers is not decreased. 661 33

The emphysema associated with the inherited serum deficiency of alpha 1-antitrypsin appears to result from an imbalance between neutrophil elastase and its major inhibitor within the alveolar structures. In the present study we assessed the feasibility of reversing this biochemical defect within the lung via parenteral replacement therapy with an alpha 1-antitrypsin concentrate of normal plasma. A 20--40% polyethylene glycol precipitate of pooled human donor plasma was used to obtain an enriched alpha 1-antitrypsin concentrate devoid of hepatitis B antigen and immunoglobulins. Using this material, five individuals with severe serum alpha 1-antitrypsin deficiency (PiZ phenotype) and advanced emphysema received 4 g of alpha 1-antitrypsin intravenously at weekly intervals for four doses. During this period of weekly replacement therapy alpha 1-antitrypsin serum levels were maintained at greater than or equal to 70 mg/dl, the level likely required for effective antielastase protection of the lung. In addition, assessment of lower respiratory tract antielastase activity by bronchoalveolar lavage demonstrated that parenteral replacement of alpha 1-antitrypsin resulted in establishment of effective antielastase activity within the alveolar structures. There were no untoward side effects consequent to this approach to the replacement therapy of alpha 1-antitrypsin. These results demonstrate that the parenteral replacement of alpha 1-antitrypsin provides a means of obtaining elastase-antielastase balance within the lung of individuals with this serum protease inhibitor deficiency.
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PMID:Replacement therapy of alpha 1-antitrypsin deficiency. Reversal of protease-antiprotease imbalance within the alveolar structures of PiZ subjects. 702 85

This report describes a radioimmunological method for the measurement of the protease inhibitor antileukoprotease in nanogram quantities. Antileukoprotease, previously found in bronchial secretions, has now also been found in serum using this radioimmunologic technique. In healthy blood donors the serum level was 126 micrograms/l. The serum immunoreactive antileukoprotease was found in a free form and did not show any antigenic cross reaction with the normal plasma protease inhibitors. Further, it was also found to be active and to form a complex with active human granulocyte elastase.
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PMID:A radioimmunoassay for measurement and characterization of human antileukoprotease in serum. 734 85

The effect of solid-phase fibrin on the inactivation of plasmin, miniplasmin, and neutrophil leukocyte elastase (PMN-elastase) by plasma protease inhibitors (alpha 2-antiplasmin, alpha 1-protease inhibitor, alpha 2-macroglobulin) was studied. In Hanks' balanced salt solution, fibrin reduces the second-order rate constant for the inhibition of PMN-elastase by alpha 1-protease inhibitor from 8,760 x 10(4) to 4 x 10(4) M-1.s-1 and by alpha 2-macroglobulin from 121 x 10(4) to 1.8 x 10(4) M-1.s-1. The rate constant for miniplasmin inactivation by alpha 2-antiplasmin decreases from 99 x 10(4) to 1 x 10(4) M-1.s-1, by alpha 2-macroglobulin from 78 x 10(4) to 1.8 x 10(4) M-1.s-1, and by alpha 1-protease inhibitor from 0.11 x 10(4) M-1.s-1 to 0. Plasmin bound to fibrin is completely protected against alpha 2-macroglobulin and alpha 1-protease inhibitor, whereas the rate constant for the inactivation by its primary plasma inhibitor alpha 2-antiplasmin is reduced from 430 x 10(4) to 1.08 x 10(4) M-1.s-1. The competition of substrate and inhibitor for the enzyme was also studied, using fibrin preincubated with inhibitor. Under our pseudo-first-order experimental conditions, fibrin completely eliminates those interactions, the second-order rate constant of which is 1.1 x 10(5) M-1.s-1 or less in a system without fibrin surface.
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PMID:Regulation of fibrinolytic activity of neutrophil leukocyte elastase, plasmin, and miniplasmin by plasma protease inhibitors. 751 29

The effect of heparin on the inactivation rates of fibrin-bound plasmin, miniplasmin and neutrophil leukocyte elastase (PMN-elastase) by their plasma inhibitors was studied. While plasmin and miniplasmin bound to fibrin are not inactivated by antithrombin, heparin (800 nM) makes these enzymes available for the inhibitor; the second-order rate constant increases from zero to 1.3 x 10(3) M-1 s-1 and 3.3 x 10(3) M-1 s-1, respectively. Heparin slightly increases the rate of fibrin-bound enzyme inactivation by plasmin inhibitor. alpha 1-Protease inhibitor, on the other hand, is unable to inactivate plasmin or miniplasmin bound to fibrin and heparin has no facilitating effect. In the case of PMN-elastase, heparin (300 nM) further increases enzyme protection against alpha 1-protease inhibitor; the rate constant decreases from 41 x 10(3) M-1 s-1 to 23 x 10(3) M-1 s-1. alpha 2-Macroglobulin inhibits fibrin-bound miniplasmin and PMN-elastase with a second-order rate constant of 1.8 x 10(4) M-1 s-1 and heparin (300 nM) increases the rate insignificantly for miniplasmin and by a factor of two for PMN-elastase. It is remarkable that plasmin bound to fibrin is not inhibited by alpha 2-macroglobulin independently of the presence of heparin. On the basis of the reported kinetic data a lifespan of 420 s for plasmin, 66 s for miniplasmin and 4 s for PMN-elastase was calculated, when the enzymes are bound to fibrin in the presence of the four protease inhibitors at physiological plasma concentration. If heparin is present (300 nM) these values decrease to 240 s for plasmin and 42 s for miniplasmin, whereas that of PMN-elastase is unchanged. Thus, the present in vitro kinetic model suggests an antifibrinolytic effect of heparin in a plasma milieu.
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PMID:Heparin modulation of the fibrinolytic activity of plasmin, miniplasmin and neutrophil leukocyte elastase in the presence of plasma protease inhibitors. 753 86

The hematopoietic neutral serine proteases leukocyte elastase and cathepsin G are synthesized as inactive precursors, but become activated by removal of an amino-terminal dipeptide and are stored in granules. Moreover, the pro forms of elastase and cathepsin G show carboxyl-terminal prodomains of 20 and 11 amino acids, respectively, which are not present in the mature enzymes. To investigate mechanisms of processing, activation, and granular targeting, we have utilized transgenic expression of myeloid serine proteases in the rat basophilic/mast cell line RBL-1 (Gullberg, U., Lindmark, A., Nilsson, E., Persson, A.-M., and Olsson, I. (1994) J. Biol. Chem. 269, 25219-25225). Leukocyte elastase was stably expressed in RBL-1 cells, and the translation products were characterized by biosynthetic labeling followed by immunoprecipitation, SDS-polyacrylamide gel electrophoresis, and fluorography. Processing of a main pro form of 34 kDa into mature 31- and 29-kDa forms was demonstrated. Translocation of mature forms to granule-containing fractions was shown by subcellular fractionation experiments. The processed forms were enzymatically active, judging by the occurrence of amino-terminal processing demonstrated by radiosequence analysis, the acquisition of affinity for the protease inhibitor aprotinin, and the appearance of elastase activity in transfected RBL cells. To investigate the function of the carboxyl-terminal prodomains, deletion mutants of leukocyte elastase and cathepsin G lacking the carboxyl-terminal extension were constructed and transfected into RBL cells. Our results show that as full-length proteins, the deletion mutants were converted to active enzymes and transferred to granules with kinetics similar to that of wild-type enzymes. We conclude that human leukocyte elastase and cathepsin G are converted into enzymatically active forms when expressed in RBL cells and targeted for storage in granules; the carboxyl-terminal prodomains are necessary neither for enzymatic activation nor for targeting to granules in RBL cells.
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PMID:Carboxyl-terminal prodomain-deleted human leukocyte elastase and cathepsin G are efficiently targeted to granules and enzymatically activated in the rat basophilic/mast cell line RBL. 753 7

Secretory leucocyte protease inhibitor, SLPI, is a low-molecular-weight, acid-stable protein present in the liquid part of fresh human ejaculate but not demonstrable in the gel structure. No fragmentation of SLPI occurred during gel dissolution, but a slow proteolytic cleavage of SLPI was seen on incubation of the liquified semen at 37 degrees C. The same pattern of degradation products was seen after incubation of SLPI with prostatic secretion and also with purified prostate-specific antigen, PSA. We could identify Arg 20-Tyr 21 and Met 73-Leu 74 to be the primary cleavage sites upon proteolytic modification of SLPI by purified PSA. However, we did not find any inhibition of the enzymatic activity of PSA by SLPI, even at a 100-fold molar excess of the inhibitor. The slow degradation of SLPI facilitated sampling and the reliable determination of the normal level of SLPI in seminal plasma, which was about 20 mg/L. We investigated the glandular origin of SLPI in the genital tract by immunocytochemistry. A strong immunostaining for SLPI was demonstrated in epithelial cells within the glandular lumina of the prostate gland, seminal vesicles, and epididymis but not in the stromal parts of these glands. In addition the immunostaining was also detected in the deferent ducts and the germinal epithelium of the testes. Taking into account that SLPI is a strong inhibitor of several proteases, including leukocyte elastase and cathepsin G, the results suggest that SLPI has a local protective function against proteolytic degradation of the male reproductive tract tissues during inflammation.
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PMID:Secretory leucocyte protease inhibitor in the male genital tract: PSA-induced proteolytic processing in human semen and tissue localization. 753 15

Polymorphonuclear neutrophils (PMN) play an important role in myocardial ischemia/reperfusion (MI/R) injury; however, the role of neutrophilic proteases is less understood. The effects of a novel serine protease inhibitor (serpin), LEX032, were investigated in a murine model of MI (20 min) and R (24 hr) injury in vivo. LEX032 is a recombinant human alpha 1-antichymotrypsin in which six amino acid residues were replaced around the active center with those of alpha-1 protease inhibitor. LEX032 has the ability to inhibit both neutrophil elastase and cathepsin G, two major neutral serine proteases in neutrophils, as well as superoxide generation. LEX032 (25 or 50 mg/kg) administered i.v. 1 min before reperfusion significantly attenuated myocardial necrotic injury evaluated by cardiac creatine kinase loss compared to MI/R rats receiving only vehicle (P < .001). Moreover, cardiac myeloperoxidase activity, an index of PMN accumulation, in the ischemic myocardium was significantly attenuated by LEX032 as compared with rats receiving vehicle (P < .001). LEX032 also moderately attenuated leukotriene B4-stimulated PMN adherence to rat superior mesenteric artery endothelium and markedly diminished superoxide radical release from LTB4-stimulated PMN in vitro. In a glycogen-induced rat peritonitis model, LEX032 (50 mg/kg) significantly attenuated PMN transmigration into the peritoneal cavity in vivo. In conclusion, the recombinant serine protease inhibitor, LEX032, appears to be an effective agent for attenuating MI/R injury by inhibiting neutrophil-accumulation into the ischemic-reperfused myocardium and by inactivating cytotoxic metabolites (proteases and superoxide radical) released from neutrophils.
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PMID:Cardioprotection by a novel recombinant serine protease inhibitor in myocardial ischemia and reperfusion injury. 756 95


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