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)

A series of tripeptides possessing trifluoromethyl or aryl ketone residues at P1 were prepared and evaluated both in vitro and in vivo as potential inhibitors of human leukocyte elastase (HLE). Tripeptides containing non naturally occurring N-substituted glycine residues at the P2-position have been demonstrated to be potent in vitro inhibitors of HLE, with IC50 values in the submicromolar range. Sterically demanding substituents on the P2-nitrogen have no detrimental effect on in vitro potency. The inhibition process presumably acts via hemiketal formation with the active site Ser195 of HLE, and is facilitated by the strongly electron withdrawing trifluoromethyl functionality. Deletion of the amino acid at the P3-subsite region affords inactive compounds. Valine is the preferred residue at the P1-position, whereas the corresponding glycine, alanine, alpha,alpha-dimethylglycine, or phenylalanine analogues are all inactive. The compounds described herein all confer a high degree of in vitro specificity when tested against representative cysteine, aspartyl, metallo, and other serine proteases. One of the most potent in vitro inhibitors is (3RS)-N-[4-[[[(4-chlorophenyl)sulfonyl]amino]carbonyl]phenyl] oxomethyl]-L-valyl-N-(2,3-dihydro-1H-inden-2-yl)glycine N-[3-(1,1,1-trifluoro-4-methyl-2-oxopentyl)]amide (20i; BI-RA-260) (IC50 = 0.084 microM). Compound 20i was also tested in hamsters in an elastase-induced pulmonary hemorrhage (EPH) model. In this model, intratracheal (it.) administration of 20i, 5 min prior to HLE challenge, effectively inhibited hemorrhage in a dose-dependent manner with an ED50 of 4.8 micrograms. The inhibitor 20i, 20 micrograms administered it. 24, 48, and 72 h prior to HLE challenge, exhibits significant inhibition against hemorrhage at all time points (97%, 64% and 49%, respectively). In a 21-day chronic model of emphysema in hamsters, 200 micrograms of HLE administered it. caused an elastase-induced emphysema in the lungs which can be quantitated histologically utilizing image analysis. In this assay, 20i significantly inhibited pulmonary lesions associated with septal destruction and increased alveolar spaces, when dosed at 20 micrograms it. 5 min prior to challenge with HLE.
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PMID:Inhibition of human leukocyte elastase (HLE) by N-substituted peptidyl trifluoromethyl ketones. 154 92

Based on available knowledge, this study shows that alpha-1-proteinase inhibitor (alpha 1-PI) plays an important role in protecting lung elastin from elastolytic proteinases, particularly human neutrophil elastase (HNE). Studies previous to this one showed that alpha 1-PI was very susceptible to inactivation by oxidants. We sought to use this oxidant sensitivity as an in vivo marker for ozone (O3) and nitrogen dioxide (NO2) exposure. The mechanism of alpha 1-PI inactivation by O3 and NO2 was examined to provide insight concerning the pathogenesis of oxidant-mediated lung damage. Attention also was focused on the bronchial leukocyte proteinase inhibitor (BLPI), which inhibits HNE in the bronchial secretions. Careful examination of blood plasma samples from individuals exposed to 0.5 ppm O3 for four hours on two consecutive days failed to detect any inactivation of alpha 1-PI. This result showed that blood alpha 1-PI was not a satisfactory marker for O3 exposure, but, more importantly, demonstrated that inhaling O3 for short periods does not grossly inactivate this important protein. Studies on BLPI showed that it is a significant inhibitor of HNE and probably plays a more important role in protecting the lung than previously thought. BLPI, like alpha 1-PI, was found to be inactivated by oxidants, including O3 and NO2. The mechanism of O3 inactivation of leukocyte proteinase inhibitors was studied using alpha 1-PI, alpha-1-antichymotrypsin (alpha 1-Achy), BLPI, and Eglin C. While all these inhibitors differed in structure, the concentrations of O3 required for inactivation were essentially the same, except for alpha 1-Achy, which only lost half of its inhibitory activity. It would seem from these results that O3 can damage proteins via the oxidation of any of the following: tryptophan (Trp), methionine (Met), tyrosine (Tyr), or histidine (His) residues. Interestingly, Eglin C, which does not have oxidizable amino acids in its inhibitory active site, was inactivated by the same amount of O3 as BLPI, BLPI was easily inactivated by a methionine-specific oxidant, suggesting an important role for methionine in this inhibitor. In vitro exposure of alpha 1-PI and BLPI to 800 moles of NO2 per mole of inhibitor resulted in 35% and 50% losses of HNE inhibitory activity, respectively. Tryptophan was destroyed by NO2 and studies are in progress to examine effects on other amino acids.
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PMID:Effects of ozone and nitrogen dioxide on human lung proteinase inhibitors. 326 87

Twelve patients with terminal uremia (8 females and 4 males) treated with chronic maintenance hemodialysis, were extensively studied during two successive dialyses with alternate use of either a Cuprophan (CP) based membrane, or a Polycarbonate (PC) membrane. Arterial plasma levels of total hemolytic complement, complement factors C3d and C5a, and granulocyte derived elastase were determined immediately before dialysis and sequentially during the entire procedure. Effluent line from the hemodialyzer was similarly sampled. Collected samples were centrifuged immediately at the bedside and instantly frozen in liquid nitrogen in order to preserve labile plasma components of complement. Analysis of the overall results shows that initial arterial leukopenia and generation of C5a in the hemodialyzer, as well as maximal values of hemodialysis-induced free plasma C3d and granulocyte elastase are related. Reflecting differences in biocompatibility, CP membranes were shown to induce significantly more leukopenia, increase in plasma free C3d, generation of C5a, and release of granulocyte-derived elastase. These results indicate that activation of complement, leukopenia, and release of granulocyte derived elastase are interlinked pathophysiological mechanisms of importance for acute deterioration of pulmonary function during hemodialysis, and that this condition is closely related to adult respiratory distress syndrome (ARDS).
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PMID:Adult respiratory distress-like syndrome during hemodialysis: relationship between activation of complement, leukopenia, and release of granulocyte elastase. 385 Aug 56

Human neutrophil elastase and other neutrophil granule constituents are internalized by human alveolar macrophages in vitro via receptor-mediated endocytosis, and immunoreactive neutrophil elastase is detectable within alveolar macrophages freshly harvested from human smokers. To gain insight into the potential role of neutrophil elastase bound by alveolar macrophages in the pathogenesis of connective tissue proteolysis, we have chosen hypoxia as a model of macrophage injury and have studied its effect upon the fate of bound neutrophil elastase. We found (1) that in a 3-h incubation after brief exposure to neutrophil elastase, control alveolar macrophages partially degraded bound enzyme, but they also released intact, enzymatically active, elastase in small amounts; (2) that release of TCA-insoluble radiolabeled elastase and elastase activity was enhanced fivefold and twofold over control, respectively, by alveolar macrophage injury during a 3-h incubation in humidified nitrogen; (3) that enzymatic activity of bound neutrophil elastase was largely masked by human neutrophil elastase-inhibitory activity of macrophage cell extracts. The data suggest (1) that the fate of neutrophil elastase bound to alveolar macrophages may be modulated by the local tissue environment; (2) that noxious agents may cause proteolytic tissue injury in the vicinity of alveolar macrophages by enhancing release of bound neutrophil elastase; (3) that alveolar macrophages may participate in the pathogenesis of centrilobular pulmonary emphysema by serving as a vector for neutrophil elastase, even if elastase activity is not detectable in alveolar macrophage lysates.
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PMID:Hypoxic injury to human alveolar macrophages accelerates release of previously bound neutrophil elastase. Implications for lung connective tissue injury including pulmonary emphysema. 634 81

The objective of this study was to evaluate and compare the derangement of body homeostatis and the inflammatory response after different types of traumatological operations in patients with multiple injuries. These were determined in a total of 60 operations. The procedures comprised osteosynthesis of the femur (n = 28), the pelvic girdle (n = 11) the spine (n = 8), and facial and basal skull reconstructions (n = 13). Specific and unspecific parameters of the inflammatory response were determined on the morning of the operation, immediately after the procedure, every 6 h on the 1st day and 48 h after the end of surgery. After all types of operations (pelvis, femur, spine, face/basal skull) significant alterations were observed for neutrophil elastase, C-reactive protein, interleukin 6, interleukin 8, antithrombin III, partial thromboplastin time and other parameters. The degree of postoperative changes differed significantly (Kruskal-Wallis test, P < 0.05) among the four types of operations for lactate, heart rate, PO2/FiO2 ratio and nitrogen excretion and showed a strong discriminating tendency for neutrophil elastase and C-reactive protein. The changes were most pronounced after operations on the pelvic girdle, followed by procedures in the femoral, spinal, and facial/basal skull regions. We conclude that a considerable inflammatory response and pronounced disturbance of body homeostasis follow traumatological operative procedures, varying in severity with the type of surgery. Several parameters allow quantitation of the surgical trauma and differentiation between different operations/regions. Further research should focus on the interrelationship between pre-existing preoperative inflammation and the additional trauma inflicted by surgery in patients with severe injuries.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Postoperative homeostatic imbalance after trauma surgical interventions of various degrees in polytrauma]. 748 29

A series of peptidyl alpha-ketobenzoxazoles were synthesized and evaluated for their in vitro and in vivo inhibition of human neutrophil elastase (HNE). These compounds inhibit HNE by forming both a covalent bond between the ketone carbonyl carbon atom and the hydroxyl group of Ser-195 and a hydrogen bond between the benzoxazole nitrogen atom and His-57. Appending to the parent benzoxazole ring a variety of substituents which spanned a range of physicochemical properties had only a modest effect on in vitro potency (Ki = 3-0.4 nM). This apparent lack of a significant effect is believed to result from the fact that any increased ketone carbonyl activation by the ring substituent is counter balanced by a corresponding decrease in the hydrogen-bonding ability of the benzoxazole nitrogen atom. In contrast to the results in vitro, maximizing in vivo activity was critically dependent upon the choice of the benzoxazole ring substituent. Several substituted peptidyl alpha-ketobenzoxazoles effectively inhibited HNE-induced lung injury when administered intratracheally 24 h prior to the enzyme.
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PMID:Peptidyl alpha-ketoheterocyclic inhibitors of human neutrophil elastase. 3. In vitro and in vivo potency of a series of peptidyl alpha-ketobenzoxazoles. 756 31

A series of peptidyl alpha-ketoheterocycles were synthesized and evaluated for their in vitro inhibition of human neutrophil elastase (HNE). Several heterocycles, including oxazoline and benzoxazole, afforded extremely potent inhibitors of HNE (1p-r) with nanomolar to subnanomolar Ki values. The structure-activity relationships revealed that for compounds with a Ki < 1000 nM potency tends to be positively correlated with the sigma I value of the heterocycle. Furthermore, the results in this study support the hypothesis that, in the covalent enzyme-inhibitor adduct, the azole nitrogen atom of the inhibitor heterocycle participates in a hydrogen-bonding interaction with the active-site His-57.
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PMID:Peptidyl alpha-ketoheterocyclic inhibitors of human neutrophil elastase. 2. Effect of varying the heterocyclic ring on in vitro potency. 783 43

The effects of ozone (O3) and nitrogen dioxide (NO2) on the solubility and proteolytic susceptibility of elastin were examined to better understand how these oxidant air pollutants might damage the lung. In vitro O3 exposures at pH 7.4 resulted in the complete solubilization of elastin, but NO2 had no effect on solubility. The initial solubilization rate was 65 micrograms/mumol of O3, which increased to 150 micrograms/mumol in the midregion of a sigmoidal solubilization curve. Peptide fragments of the O3-solubilized elastin ranged in size from 5 to 20 kD. The conversion of insoluble elastin into soluble fragments by O3 was not due to the destruction of desmosine crosslinks. The effect of O3 on the proteolytic susceptibility of elastin was measured using insoluble elastin recovered from exposures that resulted in 5.3%, 12.8%, and 26.3% solubilization. Human neutrophil elastase (HNE) digested the remaining insoluble elastin samples 4.3, 6.0, and 9.8 times faster than unexposed elastin. In contrast, NO2-exposed elastin was no more susceptible to digestion by HNE. Ascorbate, EDTA, and uric acid reduced the proteolytic susceptibility of O3-exposed elastin, but mannitol afforded no protection. These findings indicate that the inhalation of O3 may contribute to lung disease by directly damaging elastin and by increasing its susceptibility to proteolysis, whereas NO2 probably damages lungs via alternative mechanisms.
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PMID:Ozone, but not nitrogen dioxide, fragments elastin and increases its susceptibility to proteolysis. 792 32

Nitrogen dioxide (NO2), an air pollutant produced by burning fossil fuels and a component of cigarette smoke, is thought to contribute to the pathogenesis of pulmonary diseases, such as emphysema. In order to gain information on the mechanism by which NO2 damages the lung and proteins vital to its function, as well as its reaction with proteins in general, in vitro exposures of alpha-1-proteinase inhibitor (alpha 1PI), elastin, poly-L-lysine, and poly-L-arginine were performed. The ability of alpha 1PI to inhibit its natural physiological target, human neutrophil elastase (HNE), declined with exposure to 54% of the control value at molar ratios of NO2:alpha 1PI of 400:1 and greater. Exposure of alpha 1PI to NO2 resulted in a 50% loss of immunoreactivity with either monoclonal or polyclonal antibodies in an enzyme-linked immunosorbent assay at molar ratios of NO2:alpha 1PI of 100:1 and greater. The results of parallel O-phthalaldehyde and bicinchoninic acid protein assays as well as amino acid analysis on control and NO2-exposed alpha 1PI suggested a reactivity of NO2 with lysine residues. Elastin and poly-L-lysine were labeled by reductive methylation of amino groups with [3H]HCHO prior to treatment with NO2 in aqueous solutions at physiological pH. NO2 exposure of elastin resulted in the solubilization of 84% of the associated radioactivity of which 79% was identified as [3H]methyllysine by amino acid analysis. After NO2 exposure of poly-L-[3H]lysine, gel filtration chromatography revealed that the 50,000 M(r) poly-L-[3H]lysine had been degraded to small peptides of 1-3000 M(r). Similarly, after NO2 exposure of unlabeled poly-L-arginine, gel filtration chromatography, and total peptide analysis revealed that the 47,500 M(r) peptide was also partially degraded to peptides. These results suggest that NO2 reacts with the epsilon-amino groups of Lys residues (primary amines) and with the amide nitrogen (secondary amines) of surface-exposed Lys and Arg residues in the peptide backbone to result in peptide bond cleavage. These findings are the first indication of NO2-mediated peptide degradation and provide additional data on the potential of NO2 to damage proteins vital to the function of the lung in an in vitro exposure system.
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PMID:Nitrogen dioxide reactivity with proteins: effects on activity and immunoreactivity with alpha-1-proteinase inhibitor and implications for NO2-mediated peptide degradation. 832 82

We investigated the effect of activated protein C (APC) on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats to investigate the possible usefulness of APC as a treatment for adult respiratory distress syndrome. Intravenously administered LPS (5 mg/kg) significantly increased pulmonary vascular permeability. APC prevented the LPS-induced increase in pulmonary vascular permeability observed at 6 hours. Heparin plus antithrombin III (ATIII) and active site-blocked factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, inhibited LPS-induced coagulopathy but did not prevent LPS-induced pulmonary vascular injury. LPS-induced pulmonary vascular injury was significantly attenuated in rats with nitrogen mustard-induced leukocytopenia and in rats treated with ONO-5046, a potent granulocyte elastase inhibitor. Administration of LPS also increased pulmonary accumulation of leukocytes, as evaluated by measurement of myeloperoxidase activity in the lungs. APC significantly reduced LPS-induced increases in pulmonary accumulation of leukocytes at 1 hour. Neither ATIII plus heparin nor DEGR-Xa inhibited leukocyte accumulation. Active site-blocked APC (DIP-APC) prevented neither the LPS-induced pulmonary accumulation of leukocytes nor the LPS-induced increase in pulmonary vascular permeability. These results suggest that the mechanism of APC inhibition of LPS-induced pulmonary vascular injury was independent of its anticoagulant activity and was related to its ability to inhibit accumulation of leukocytes. In addition, these findings suggest that the serine protease activity of APC may be essential to its inhibitory effect on LPS-induced pulmonary accumulation of leukocytes and subsequent pulmonary vascular injury.
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PMID:Activated protein C attenuates endotoxin-induced pulmonary vascular injury by inhibiting activated leukocytes in rats. 855 86


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