Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.27 (thermolysin)
 1,894 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two glycoproteins having trypsin-protein esterase activity were purified to apparent homogeneity from murine plasma. One was alpha-macroglobulin, a homologue of human alpha-2-macroglobulin, while the other, tentatively named murinoglobulin, did not correspond to any of the known plasma protease inhibitors that have been well characterized in men or other mammals. Murinoglobulin contained about 7.6% carbohydrate and was composed of a single-polypeptide chain of Mr = 180,000 as judged by the equilibrium sedimentation analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Murinoglobulin did not cross-react immunologically with mouse alpha-macroglobulin nor with human alpha-2-macroglobulin. Protease-inhibiting properties of murinoglobulin were compared with those of mouse alpha-macroglobulin and human alpha-2-macroglobulin. All the three proteins inhibited trypsin, papain, and thermolysin, although they differed considerably in both the degree of inhibition and the binding stoichiometry of protease-inhibitor complexes. The two macroglobulins inhibited pepsin at pH 5.5, whereas murinoglobulin was inactivated at this pH. Murinoglobulin was more sensitive to methylamine than the two macroglobulins. No protein corresponding to murinoglobulin was detected in human plasma.
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PMID:Murinoglobulin, a novel protease inhibitor from murine plasma. Isolation, characterization, and comparison with murine alpha-macroglobulin and human alpha-2-macroglobulin. 257 55

Pseudomonas toxin is produced as a proenzyme which is cytotoxic for cells in culture but must be activated to express full enzymatic activity. The ability of purified pseudomonas alkaline protease and elastase or of culture filtrates of two strains of Pseudomonas aeruginosa to modify the activity of pseudomonas toxin was examined. Two parameters of toxin activity were followed: enzymatic activity, i.e., the adenosine diphosphate (ADP) ribosylation of elongation factor 2, and biological activity, i.e., inhibition of protein synthesis in cultured mouse fibroblasts. Biological activity of toxin depends upon an intact toxin molecule, whereas enzyme activity requires only a functional A region. Incubation with purified pseudomonas proteolytic enzymes did not alter either enzymatic or biological activity. The toxin is not refractory to the action of all proteolytic enzymes, since thermolysin rapidly destroyed the toxin molecule. Treatment of toxin with culture filtrates of P. aeruginosa reduced ADP ribosylation activity, but increased the ability of toxin to inhibit protein synthesis in cell monolayers. Incubation of culture filtrates with one of the protease inhibitors alpha-2-macroglobulin or phosphoramidon did not alter the effect of the filtrates on biological activity. Alpha-2-macroglobulin, however, caused a fourfold stimulation of ADP ribosylation activity of the toxin. We conclude that pseudomonas alkaline protease and elastase are not responsible for the modifications in toxin activity induced by culture filtrates of P. aeruginosa; the factors responsible have not yet been identified, but are not inactivated by phosphoramidon or alpha-2-macroglobulin.
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PMID:Resistance of exotoxin A to purified Pseudomonas proteolytic enzymes. 615 7

We report the identification of the first representative of the alpha-2-macroglobulin family identified in terrestrial invertebrates. An abundant acidic glycoprotein was isolated from the plasma of the soft tick Ornithodoros moubata. Its molecular mass is about 420 kDa in the native state, whereas in SDS/PAGE it migrates as one band of 190 kDa under nonreducing conditions and a band of 92 kDa when reduced. Chemical deglycosylation reveals that it is composed of two different subunits, designated A and B. The N-terminal amino-acid sequence of subunit A is similar to the N-terminus of invertebrate alpha-2-macroglobulin. Sequence analysis of several internal peptides confirms that the tick protein belongs to the alpha-2-macroglobulin family, and the protein is therefore referred to as tick alpha-macroglobulin (TAM). Functional analyses strengthen this assignment. TAM inhibits trypsin and thermolysin cleavage of the high-molecular-weight substrate azocoll in a manner similar to that of bovine alpha-2-macroglobulin. This effect is abolished by pre-treatment of TAM with methylamine. In the presence of TAM, trypsin is protected against active-site inhibition by soybean trypsin inhibitor. We cloned and sequenced a PCR product containing sequences from both subunits and spanning the N-terminus of subunit B and the putative 'bait region' (a segment of alpha-2-macroglobulin which serves as target for various proteases). This indicates that the two subunits are generated from a precursor polypeptide by post-translational processing.
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PMID:Characterization of an alpha-macroglobulin-like glycoprotein isolated from the plasma of the soft tick Ornithodoros moubata. 1063 16