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 specific radioimmunoassay has been developed for determination of human granulocyte elastase in blood. THE granulocyte elastase employed as radioiodinated tracer in the assay was inactivated with diisopropylfluorophosphate in order to prevent binding of the tracer to the serum inhibitors alpha2-microglobulin and alpha1-anti-trypsin, while still retaining its immunoreactivity. The labelled tracer showed, however, a pronounced tendency to nonspecific binding to serum proteins such as albumin and alpha2-macroglobulin and also to the Sephadex particles. The binding of the labelled tracer to alpha2-macroglobulin caused a false increase in the immunoreactive granulocyte elastase in serum. But the binding of the labelled tracer and its consequences could be circumvented by increasing the NaCl concentration of the reaction mixtures and/or gel filtration buffers. Freshly drawn normal human serum contains about 135 microgram granulocyte elastase/l measured as diisopropylfluorophosphate-inactivated granulocyte elastase. The results of experiments in which serum was fractionated by Sephadex G-100 gel filtration suggest that essentially all of the immunoreactive material in normal human serum is granulocyte elastase bound by alpha1-antitrypsin. This finding implies that granulocyte elastase is released from the cells in an active form and then rapidly bound by the inhibitors.
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PMID:Immunoreactive granulocyte elastase in human serum. 73 Jan 11

Bronchoalveolar lavage (BAL) fluid was obtained from 24 sequentially studied patients with adult respiratory distress syndrome (ARDS) for assessment of potential activating and mediating factors. Proteolytic activity of the fluids was observed by measuring cleavage of radiolabeled proteins of the contact (Hageman factor) and complement systems. Proteolytic activity was observed in 17 of 24 (71%) patients with ARDS, and BAL fluid of the 7 ARDS patients without demonstrable, active, enzyme exhibited inhibitory activity for the proteolytic activity. The enzymes cleaved Hageman factor, prekallikrein, plasminogen, high molecular weight kininogen, C4, C3, C5, and Factor B of the complement system. Cleavage of the contact system proteins producted fragments similar or identical in size to the fragments observed during activation of these molecules, although continued incubation invariably reduced the protein to small peptide fragments. None of 7 normal individuals, and 29 of 99 patients (29%) with other forms of pulmonary disease contained measurable enzymes. The proteolytic activity in BAL fluid of ARDS patients was blocked by diisopropylphosphofluoridate (0.1 mM), Trasylol, soybean trypsin inhibitor, and normal plasma, or plasma deficient in inhibition of the first component of complement. Alpha(1)-proteinase inhibitor (alpha1-PI)-deficient plasma failed to inhibit the proteolytic activity and addition of alpha1-PI to the deficient plasma reconstituted the inhibition. MUCH OF THE PROTEOLYTIC ACTIVITY OF THE BAL FLUID FROM ARDS PATIENTS WAS IDENTIFIED AS NEUTROPHIL ELASTASE: the fluids cleaved elastin and synthetic peptide substrate of neutrophil elastase, neutrophil elastase antigen was present in the BAL fluids as determined immunologically using antineutrophil elastase, alpha1-PI was the major inhibitor in plasma, and the enzyme was inhibited by diisopropylphosphofluoridate but not chelation. In addition, purified neutrophil elastase produced cleavage fragments of proteins of the contact system similar to those of the BAL fluids. In each of the seven BAL fluids of ARDS patients that did not reveal active elastase, alpha1-PI was present in active form (as determined by (125)I-trypsin binding). In 9 of the 17 patients with active elastase in the BAL fluid, alpha1-PI antigen was present in the fluid, but was inactive (no binding of (125)I-trypsin). Immunoelectrophoretic analysis of elastase and alpha1-PI throughout proteins in these BAL fluids revealed the presence of both elastase and alpha1-PI that migrated with the same R(f), suggesting the presence of an enzyme-inhibitor complex. Free, inactive alpha1-PI was also observed in these fluids. The data reveal that in BAL fluids from all 24 patients with ARDS, leukocytic elastase and/or alpha1-PI exist. A complex of elastase and alpha1-PI was observed in BAL fluids, and in some cases where active enzyme and alpha1-PI coexisted, free, but inactive alpha1-PI was present.
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PMID:Studies on the pathogenesis of the adult respiratory distress syndrome. 703 51