Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study demonstrates that a serine endopeptidase of pancreatic origin (elastase 2) circulates in human blood. A specific and highly sensitive radioimmunoassay has been developed for pancreatic elastase 2 in human serum. The inactivation of elastase 2 employed as radioiodinated tracer with an active site-specific reagent (phenylmethanesulfonyl fluoride) was necessary to prevent its binding by serum alpha1-antitrypsin and alpha2-macroglobulin while maintaining its immunoreactivity. The assay is based upon competition of standard human pancreatic elastase 2 with 125I-labeled phenylmethanesulfonyl elastase 2 for specific antibody binding sites, after which a second antibody precipitation step is used to separate bound from free 125I-labeled phenylmethanesulfonyl elastase 2. The minimum detectable concentration of elastase 2 was 0.9 ng/ml. The average normal fasting serum level determined was 71 ng/ml, approximately 80-fold greater than the minimum detectable amount. The form of radioimmunoassayable elastase 2 in normal human serum has been investigated by gel filtration of serum samples on Sephadex G-200 followed by radioimmunoassay of column fractions. The majority of the immunoreactive elastase 2 is eluted from G-200 in the void volume. While a minor amount of elastase 2 is eluted in a position consistent with alpha1-antitrypsin-elastase 2 complex, no free elastase or free proelastase is detectable. Addition of exogenous elastase 2 to normal serum prior to gel filtration on G-200 produced an increase only in the peak of radioimmunoassayable elastase bound to alpha1-antitrypsin. In vitro experiments have demonstrated that while elastase 2 bound to alpha1-antitrypsin is immunologically reactive, alpha2-macroglobulin-bound elastase 2 cross-reacts less than 2% in this radioimmunoassay. The assay has been shown to be specific for elastase 2. Human pancreatic elastase 1, anionic trypsin, chymotrypsin I, and chymotrypsin II do not cross-react in this assay system. The major advantages of this radioimmunoassay over enzymatic assays are its high sensitivity and ability to measure the enzyme in terms of its total protein concentration.
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PMID:Pancreatic elastase in human serum. Determination by radioimmunoassay. 83 29

The cathepsin B like proteinase present in ascitic fluid of a patient with neoplasia has been purified and characterized after pepsin activation. From this fluid we have prepared the low molecular weight (LMW) cysteine-proteinase inhibitors. Three major inhibitor forms were found with isoelectric points of 7.4, 5.4, and 5.1, respectively. The interaction of the enzyme with the former inhibitor was studied because this inhibitor was the most abundant. The Ki value was found to be 4.3 X 10(-8) M. Two molecules of this proteinase were bound by one molecule of plasma alpha 2 macroglobulin (alpha 2M). The LMW inhibitor was able to bind to the enzyme entrapped in alpha 2M and reduced its endopeptidase activity on benzyloxycarbonyl-L-phenylalanyl-L-arginine-4-methyl-7-coumarylamide. These results may have a physiological significance in the regulation of the enzyme which, among other extracellular hydrolases, probably plays an important role in tumor invasion.
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PMID:Inhibition of the cathepsin B like proteinase by a low molecular weight cysteine-proteinase inhibitor from ascitic fluid and plasma alpha 2 macroglobulin. 243 38

The ADAMs (a disintegrin and metalloprotease) are a family of multidomain proteins with structural homology to snake venom metalloproteases. We recently described the cloning and sequencing of human ADAM 12 (meltrin alpha). In this report we provide evidence that the metalloprotease domain of ADAM 12 is catalytically active. We used the trapping mechanism of alpha2-macroglobulin to assay for protease activity of wild-type and mutant ADAM 12 proteins produced in a COS cell transfection system. We found that ADAM 12 is synthesized as a zymogen, with the prodomain maintaining the metalloprotease in a latent form, probably by means of a cysteine switch. The zymogen could be activated chemically by alkylation with N-ethylmaleimide. Cleavage of the prodomain at a site for a furin-like endopeptidase resulted in an ADAM 12 protein with proteolytic activity. The protease activity was sensitive to inhibition by 1,10-phenanthroline and could be eliminated by mutation of the critical glutamate residue at the active site. The demonstration that the ADAM 12 metalloprotease domain is functional may have important implications for future studies that explore the role of ADAM 12 protein in development and disease.
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PMID:Human ADAM 12 (meltrin alpha) is an active metalloprotease. 964 63

Legumain was recently discovered as a lysosomal endopeptidase in mammals [Chen, Dando, Rawlings, Brown, Young, Stevens, Hewitt, Watts and Barrett (1997) J. Biol. Chem. 272, 8090-8098], having been known previously only from plants and invertebrates. It has been shown to play a key role in processing of the C fragment of tetanus toxin for presentation by the MHC class-II system [Manoury, Hewitt, Morrice, Dando, Barrett and Watts (1998) Nature (London) 396, 695-699]. We examine here the specificity of the enzyme from pig kidney by use of protein, oligopeptide and synthetic arylamide substrates, all determinations being made at pH 5.8. In proteins, only about one in ten of the asparaginyl bonds were hydrolysed, and these were mostly predicted to be located at turns on the protein surface. Bonds that were not cleaved in tetanus toxin were cleaved when presented in oligopeptides, sometimes faster than an equivalent oligopeptide based on a bond that was cleaved in the protein. Legumain cleaved the bait region of rat alpha1-macroglobulin and was 'trapped' by the macroglobulin, as most other endopeptidases are, but did not interact with human alpha2-macroglobulin, which contains no asparagine residue in its bait region. Glycosylation of asparagine totally prevented hydrolysis by legumain. Specificity for arylamide substrates was evaluated with reference to benzyloxycarbonyl-Ala-Ala-Asn-aminomethylcoumarin, and the preference for the P3-position amino acid was Ala>Tyr(tertiary butyl)>Val>Pro>Phe=Tyr>Leu=Gly. There was no hydrolysis of substrate analogues containing mono- or di-N-methylasparagines, l-2-amino-3-ureidopropionic acid or citrulline in the P1 position. We conclude that mammalian legumain appears to be totally restricted to the hydrolysis of asparaginyl bonds in substrates of all kinds. There seem to be no strong preferences for particular amino acids in other subsites, and yet there are still unidentified factors that prevent hydrolysis of many asparaginyl bonds in proteins.
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PMID:Pig kidney legumain: an asparaginyl endopeptidase with restricted specificity. 1021 15

Cellular disintegrin and metalloproteinases (ADAMs) are a family of genes with a sequence similar to the snake venom metalloproteinases and disintegrins. ADAMTS-1 is a unique ADAM family protein with respect to the presence of thrombospondin type I motifs and the capacity to bind to the extracellular matrix. Because ADAMTS-1 has a potential zinc-binding motif in the metalloproteinase domain, we examined in this study whether ADAMTS-1 is an active metalloproteinase by means of the proteinase trapping mechanism of alpha2-macroglobulin. We found that the soluble type of ADAMTS-1 protein is able to form a covalent-binding complex with alpha2-macroglobulin. Furthermore, the point mutation within the zinc-binding motif of ADAMTS-1 protein eliminates its capacity to bind to alpha2-macroglobulin. These data demonstrate that the metalloproteinase domain of ADAMTS-1 is catalytically active. In addition, we showed that the removal of the pro-domain from the ADAMTS-1 precursor is impaired in the furin-deficient cell line, LoVo, and that the processing ability of the cells is restored by the co-expression of the furin cDNA. These data provide evidence that the ADAMTS-1 precursor is processed in vivo by furin endopeptidase in the secretory pathway. Consequently, ADAMTS-1 is an active metalloprotease that is associated with the extracellular matrix. This study strongly suggests that ADAMTS-1 may play a role in the inflammatory process through its protease activity.
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PMID:ADAMTS-1 is an active metalloproteinase associated with the extracellular matrix. 1037

Mutalysin II is a 22.5-kDa zinc endopeptidase isolated from Lachesis muta muta snake venom. In order to determine whether the inhibitors human alpha2-macroglobulin (alpha2-M) and rabbit antibody to mutalysin II share a common mechanism, we have investigated the inhibition of mutalysin II by these two different glycoproteins. The proteolytic activity of mutalysin II with dimethylcasein as substrate was completely inhibited by human alpha2-M and by a purified rabbit antibody to mutalysin II. The protection of fibrin(ogen) digestion by alpha2-M was slightly better than the protection offered by the antibody. In addition, the purified antibody reacted only with the metalloproteinase in bushmaster venom, as demonstrated by immunodiffusion. SDS-PAGE analysis of reduced samples showed that the interaction of mutalysin II with alpha2-M resulted in the formation of high molecular complex ( approximately 180000) and M(r) 90000 fragments generated by the venom enzyme. Also, fragments at 85 and 23 kDa were detected under non-reducing conditions after incubation of rabbit immunoglobulin with enzyme. Proteolysis of dimethylcasein as substrate revealed that the stoichiometry of inhibition was 1.0 mol of human alpha2-M and 1.5 mol of rabbit IgG antimutalysin II per mole of enzyme. Furthermore, dimethylcasein hydrolysis indicated that several viperid snake venoms, including Bothrops atrox, B. alternatus and Trimeresurus flavoviridis cross-reacted with the specific rabbit antibody to varying degrees.
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PMID:Inhibition of mutalysin II, a metalloproteinase from bushmaster snake venom by human alpha2-macroglobulin and rabbit immunoglobulin. 1154 86