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)

The total kinetic thermal stability of a protein molecule, expressed as the total free energy of activation in thermal denaturation reactions, can be separated into an intrinsic contribution of the polypeptide chain and a contribution due to the binding of calcium ions. The theory for this procedure is applied to thermal denaturation data, obtained at the pH of optimum stability, for the serine proteases, thermomycolase and subtilisin types Carlsberg and BPN', and for the zinc metalloendopeptidases, thermolysin and neutral protease A. The results, obtained from Arrhenius plots at high and low free calcium ion concentrations, reveal a considerable variation in the calcium ion contribution to the total kinetic thermal stability of the various enzymes. In the serine protease group, at 70 degrees C, the stability is largest for thermomycolase, mainly due to a relatively high intrinsic contribution. For the metalloendopeptidases the total kinetic thermal stability is largest for thermolysin, the difference between thermolysin and neutral protease A being dominated by bound calcium ion contributions. The intrinsic kinetic thermal stability of the polypeptide chain of thermolysin is considerably smaller than that of any of the serine proteases and is probably of the same order of magnitude as that of neutral protease A. Thus, the well known total kinetic thermal stability of thermolysin is due mainly to a single calcium ion (Voordouw, G., and Roche, R. S. (1975), Biochemistry 14, 4667) that binds with high affinity even at very high temperatures (K congruent to 6 X 10(7) M-1 at 80 degrees C).
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PMID:Role of bound calcium ions in thermostable, proteolytic enzymes. Separation of intrinsic and calcium ion contributions to the kinetic thermal stability. 0 92

A comparison of the partial amino-acid sequence of neutral protease A from Bacillus subtilis with the structure of thermolysin (EC 3.4.24.4) from Bacillus thermoproteolyticus reveals that these two proteins are homologous. Of 171 residues placed in neutral protease (54% of the sequence), 83 residues (49%) occur in identical positions in thermolysin, and include nine of the 13 residues previously identified as components of the active site of thermolysin. This similarity provides support for the hypothesis that the two enzymes have similar three-dimensional structures and a common mechanism of action. Since these enzymes differ markedly in their resistance to heat inactivation, a comparison of their structures may eventually provide a chemical basis for explaining the differences in their thermal stability.
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PMID:Evidence of homologous relationship between thermolysin and neutral protease A of Bacillus subtilis. 81 93

Thermolysin and neutral protease A are neutral metalloendopeptidases having similar specificity, molecular weight, metal content, and amino acid composition. Thermolysin, derived from the thermophilic organism Bacillus thermoproteolyticus, is heat inactivated at about 84 degrees whereas neutral protease A, derived from the mesophilic organism Bacillus subtilis, is inactivated at about 59 degrees. Structural analyses reveal that the two enzymes are homologous. Of the 326 residues of neutral protease A, 171 have been placed in sequence and 49% of these have been found in identical loci in thermolysin. These include many of the residues corresponding to the active site of thermolysin. The sensitivity of both enzymes to thermal inactivation is dependent upon the presence of calcium and neutral protease appears to bind less calcium than thermolysin. Structural data indicate that many of the ligands associated with calcium sites 1 and 2 (double site of thermolysin) are present in neutral protease and that calcium site 4 cannot exist in neutral protease. The structural homology and functional analogy of these two proteins support the concept that they have similar conformations. The known structure of thermolysin is used as a model to discuss structural differences which might be related to thermal stability.
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PMID:Thermal stability of homologous neutral metalloendopeptidases in thermophilic and mesophilic bacteria: structural considerations. 82 May 64

The differential cleavage of surface proteins of Borrelia burgdorferi IRS strains by several proteases was examined. Proteinase K, trypsin, chymotrypsin and thermolysin all cleaved the outer surface protein B (OspB) to undetectable levels by Coomassie Brilliant Blue staining, whereas some residual protein was detected by immunoblotting with polyclonal and monoclonal antibodies. Not even antigenic fragments were detectable by immunoblotting with 1A8 monoclonal antibody reactive with OspB. Less effective or ineffective was the cleavage of OspB by V8 protease and proteinase A, respectively. The outer surface protein A was cleaved only by proteinase K. The effect of trypsin on borreliae viability and adhesion to cultured cells was also studied. The trypsin treatment of borreliae did not impair the viability of organisms which continued to synthesize the cleaved OspB. The attachment of B. burgdorferi to HEp-2 cells was reduced by 41% after treatment with trypsin, whereas preincubation of borreliae with monoclonal antibody 1A8 and guinea pig immune serum reduced the adhesion of borreliae to the cells by 32% and 87%, respectively.
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PMID:Differential cleavage of surface proteins of Borrelia burgdorferi by proteases. 160 94

A new protease inhibitor was purified to apparent homogeneity from a culture medium of Photorhabdus luminescens by ammonium sulfate precipitation and preparative isoelectric focusing followed by affinity chromatography. Ph. luminescens, a bacterium symbiotically associated with the insect-parasitic nematode Heterorhabditis bacteriophora, exists in two morphologically distinguishable phases (primary and secondary). It appears that only the secondary-phase bacterium produces this protease inhibitor. The protease inhibitor has an M:(r) of approximately 12000 as determined by SDS-PAGE. Its activity is stable over a pH range of 3.5-11 and at temperatures below 50 degrees C. The N-terminal 16 amino acids of the protease inhibitor were determined as STGIVTFKND(X)GEDIV and have a very high sequence homology with the N-terminal region of an endogenous inhibitor (IA-1) from the fruiting bodies of an edible mushroom, Pleurotus ostreatus. The purified protease inhibitor inactivated the homologous protease with an almost 1:1 stoichiometry. It also inhibited proteases from a related insect-nematode-symbiotic bacterium, Xenorhabdus nematophila. Interestingly, when present at a molar ratio of 5 to 1, this new protease inhibitor completely inactivated the activity of both trypsin and elastase. The activity of proteinase A and cathepsin G was partially inhibited by this bacterial protease inhibitor, but it had no effect on chymotrypsin, subtilisin, thermolysin and cathepsins B and D. The newly isolated protease inhibitor from the secondary-phase bacteria and its specific inhibition of its own protease provides an explanation as to why previous investigators failed to detect the presence of protease activity in the secondary-phase bacteria. The functional implications of the protease inhibitor are also discussed in relation to the physiology of nematode-symbiotic bacteria.
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PMID:A new broad-spectrum protease inhibitor from the entomopathogenic bacterium Photorhabdus luminescens. 1110 72

Vibrio tubiashii, a pathogen of shellfish larvae and juveniles, produces several extracellular products. Here, we document that culture supernatants of several marine Vibrio species showed toxicity to oyster larvae. Treatment of these supernatants with EDTA not only severely diminished proteolytic activities, but also dramatically reduced toxicity to the larvae. Culture supernatants of metalloprotease-deficient mutants of V. tubiashii, V. cholerae, and V. splendidus were impaired in their ability to cause larval death compared to the wild type strains. Culture supernatants of Pseudomonas aeruginosa, known to contain several secreted proteases, showed virtually no toxicity to oyster larvae. Purified V. tubiashii protease A (VtpA), but not the prototype metalloprotease, thermolysin from Bacillus thermoproteolyticus, was highly toxic to the larvae. In addition, toxicity of purified VtpA was much greater for 6-d-old oyster larvae than for 16-d-old larvae. Together, these results indicated that culture supernatants of a variety of Vibrio species are highly toxic to oyster larvae and that the production of a metalloprotease is required for this effect. We propose that there are, as yet uncharacterized, specific substrates contained in larval tissue that are degraded by VtpA as well as certain homologous metalloproteases produced by other marine Vibrio species which, in turn, may contribute to vibriosis.
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PMID:Virulence of metalloproteases produced by Vibrio species on Pacific oyster Crassostrea gigas larvae. 1969 72