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

Recombinant human fibroblast pro-MMP-3 (prostromelysin-1) expressed in Chinese hamster ovary cells and the zymogen from cultured human dermal fibroblasts have been purified by monoclonal antibody immunoaffinity chromatography, and the role of Ca2+ in proenzyme activation and thermostability of the low mass catalytic domain of MMP-3 has been investigated. In the presence of high Ca2+ (5.0 mM), the organomercurial aminophenylmercuric acetate (APMA) initiated the stepwise removal of both NH2- and COOH-terminal domains from both recombinant and dermal fibroblast proenzymes, resulting in the generation of a heterogeneous family of nonglycosylated low mass truncated active enzyme species beginning at Phe83. However, in the presence of low Ca2+ (0.1 mM), incubation of recombinant pro-MMP-3 with or without APMA did not result in formation of either the high or low mass forms of active MMP-3 but resulted in complete autolysis of both enzyme species. The concentration of Ca2+ required for optimal pro-MMP-3 activation and stability of the low mass catalytic domain was 2.0 mM. The low mass truncated enzyme species containing the catalytic domain were remarkably heat-stable (90 min at 60 degrees C) in high Ca2+ (5.0 mM) but rapidly autolyzed when heated at 60 degrees C in low Ca2+ (0.1 mM). The thermostability properties of MMP-3 appeared to be specific for Ca2+, since no other divalent metal ions tested were able to confer thermostability to the low mass catalytic domain of MMP-3. From homology to the thermostable bacterial metalloprotease, thermolysin, two putative Ca2+ binding sites were found in the catalytic domain of MMP-3 and several other members of the MMP gene family. These putative Ca2+ binding sites are postulated to play an important role in stabilizing active MMP-3 and other members of the matrix metalloprotease gene family by protecting them against autolysis.
 ...
PMID:Recombinant Chinese hamster ovary cell matrix metalloprotease-3 (MMP-3, stromelysin-1). Role of calcium in promatrix metalloprotease-3 (pro-MMP-3, prostromelysin-1) activation and thermostability of the low mass catalytic domain of MMP-3. 844 Jul 30

The active site structure of the Zn-containing neutral protease from Bacillus subtilis var. amylosacchariticus (BANP) was predicted by computer-aided modeling on the basis of the three-dimensional structure of thermolysin (TLN). As expected from the high homology in amino acid sequence of the two enzymes, the overall folding of BANP was very similar to that of TLN. Glu144, Tyr158, and His228 of BANP were located near the active site Zn ion, to which three amino acid residues, His143, His147, and Glu167, were coordinated. This model is supported by the previous results that chemical modifications of Tyr158 and photooxidation of His228 of BANP markedly affect the proteolytic activity of the enzyme. Interestingly, BANP was found to be significantly less sensitive to metalloprotease inhibitors such as phosphoramidon and talopeptin. From a comparison of the enzyme-inhibitor complex models between BANP and thermolysin, it is suggested that replacement of Thr129 in TLN by Phe130 in BANP is related to difference in inhibitor sensitivity between BANP and TLN.
 ...
PMID:Zinc protease of Bacillus subtilis var. amylosacchariticus: construction of a three-dimensional model and comparison with thermolysin. 845 66

Insulin-degrading enzyme is a nonlysosomal metalloprotease that initiates degradation of internalized insulin in some cells. We previously identified a potential catalytic site containing an inversion of the Zn(2+)-binding domain of the thermolysin family (Kuo, W.-L., Gehm, B. D., and Rosner, M. R. (1991) Mol. Endocrinol. 4, 1580-1591). The role of this site in catalysis was examined by mutating one of the presumptive Zn(2+)-coordinating histidines (His108) in human insulin-degrading enzyme to leucine or glutamine, which were predicted to reduce or eliminate Zn2+ binding without substantially altering secondary structure. cDNAs for the mutant and wild-type enzymes were incorporated into an expression vector and transfected into COS cells. Expression of the transfected genes was confirmed by Northern and Western blots. In contrast to the wild-type gene, which increased insulin degradation by cell extracts and intact cells several-fold, the mutated genes had no effect on insulin degradation, indicating a loss of catalytic activity. However, the mutants' ability to bind substrate was unimpaired, as affinity labeling with 125I-insulin was increased compared to the wild type. These results suggest that an intact Zn(2+)-binding domain in human insulin-degrading enzyme is required for catalytic activity and can affect, but is not required for, substrate binding.
 ...
PMID:Mutations in a zinc-binding domain of human insulin-degrading enzyme eliminate catalytic activity but not insulin binding. 846 15

The lambda-toxin of Clostridium perfringens type B NCIB10691 was purified by ammonium sulfate precipitation, followed by size exclusion, anion-exchange, and hydrophobic interaction chromatography. The purified toxin had an apparent molecular mass of 36 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The toxin possessed casein-hydrolyzing activity, which was inhibited specifically by metal chelators, indicating that the toxin is a metalloprotease. The gene encoding the lambda-toxin (lam), which was shown by Southern analysis to be located on a 70-kb plasmid, was cloned into Escherichia coli cells. Nucleotide and N-terminal amino acid sequencing revealed that the lam gene encodes a 553-amino-acid protein, which is processed into a mature form, the molecular mass of which was calculated to be 35,722 Da. The deduced amino acid sequence of the mature enzyme contains an HEXXH motif characteristic of zinc metalloproteases and is homologous to other known enzymes belonging to the thermolysin family. The purified toxin degraded various biologically important substances, such as collagen, fibronectin, fibrinogen, immunoglobulin A, and the complement C3 component. It caused an increase in vascular permeability and hemorrhagic edema on injection into the dorsal skin of mice. These results suggest that the toxin contributes to the pathogenesis of histolytic infection by lambda-toxin-producing C. perfringens.
 ...
PMID:Purification, characterization, and primary structure of Clostridium perfringens lambda-toxin, a thermolysin-like metalloprotease. 855 45

Endothelin-converting enzyme (ECE) is a member of the zinc metalloproteinase family. It is much more specific in its protease activity than the bacterial metalloprotease thermolysin; we aim to construct a model of its active site to help to explain these differences. We aligned the sequence of human ECE with those of human neprilysin (which is 39% identical to ECE) and thermolysin. Residues believed to be important for inhibitor binding were assigned from the alignment and by analogy with structural and functional studies of these enzymes. These included a conserved IGG motif N-terminal to the zinc-binding HExxH motif, and a tyrosine residue that may be analogous to Y157 of thermolysin. We have used the program O to build a model of the active site of ECE based on the crystal structure of thermolysin.
 ...
PMID:Molecular modeling of the active site of endothelin-converting enzyme. 858 73

Cleavage by thermolysin of N-(4-methoxyphenylazoformyl)-L-leucyl-L-leucine plus some congeneric peptides provides a highly sensitive new kinetic assay for proteolytic activity. The pH dependence of Michaelis-Menten parameters Kcat and Km establishes kinetically a reverse protonation catalytic mechanism for this metalloprotease [Mock, W.L., & Aksamawati, M. (1994) Biochem. J. 302, 57-68]. An acidified water molecule (pKa of 5, seen in Km) becomes displaced by substrate carboxamide from the hypercationic Zn2+ of the enzyme, yielding potent Lewis acid activation of the peptide linkage for subsequent hydrolysis. Conversion to product is induced by the side chain of enzymic residue His 231 (pKa of 8, seen in Kcat), which provides general base catalysis for addition of H2O to the zinc-activated scissile carboxamide of the bound substrate. A previously described "superactivation" through chemical modification of the enzyme with acetylphenylalanyl-N-hydroxysuccinimide is nonexistent in the case of the new substrates, which indicates that their binding to thermolysin is largely productive, unlike normal peptides. Correct assignment of kinetically observed pKa values to active site residues, along with recognition of a predominantly nonproductive binding mode for ordinary substrates and thermolysin, forces reinterpretation of previous mechanistic formulations for the enzyme.
 ...
PMID:Arazoformyl dipeptide substrates for thermolysin. Confirmation of a reverse protonation catalytic mechanism. 865 13

Pseudomonas aeruginosa is a zinc metalloprotease which may be involved in many infection processes, especially in the lung. In order to evaluate the production of the enzyme in culture supernatants, we developed an assay using peptide derivatives; the conductimetric method was used for monitoring the enzymatic activities. Tetrapeptide derivatives were enzymatically synthesized by coupling Z-Ala2 and X-AlaR using either thermolysin or P. aeruginosa elastase itself. In these substrates, X could be phenylalanine, tyrosine, or leucine and C-protection was performed by either an amide (NH2) or a methyl (OMe) group. Z-Ala2-Phe-AlaNH2 was found to be the best substrate, giving a catalytic ratio kcat/KM of 8600 mM-1.s-1. The evaluation of the alkaline protease activity with this substrate showed that the catalytic ratio is 1000-fold lower. The sensitivity of the conductimetric method was also demonstrated with as little as 1 nM elastase (0.13 microgram), being easily and accurately detected (SD, 3.8% for 10 measurements). Furthermore, the enzymatic activity was measured in a culture supernatant from a clinical strain.
 ...
PMID:Synthetic peptide substrates for a conductimetric assay of Pseudomonas aeruginosa elastase. 866 May 69

Two monoclonal antibodies (MAbs) to a 36-kDa extracellular metalloprotease (PSCP) from Burkholderia (Pseudomonas) cepacia were found to react with thermolysin, Pseudomonas aeruginosa elastase, alkaline protease (Apr) and LasA, Serratia marcescens protease (SMP), Aeromonas hydrophila protease (AhP), and both the lethal factor (LF) and protective antigen (PA) of Bacillus anthracis on immunoblots. The MAbs were capable of neutralising the proteolytic activity of thermolysin, P. aeruginosa elastase and PSCP but not that of Apr, SMP, and AhP. These results suggest that these MAbs may be able to differentiate between the thermolysin and serralysin family of metalloproteases on the basis of their neutralisation capability and could, therefore, be useful tools in the characterisation of new bacterial proteases.
 ...
PMID:Differentiation of thermolysins and serralysins by monoclonal antibodies. 881 Sep 50

Escherichia coli peptide deformylase, a member of the zinc metalloproteases family, is made up of an active core domain composed of 147 residues and of an additional and dispensable C-terminal tail of 21 residues. The three-dimensional structure of the catalytic core could be studied by NMR. 1H and 15N NMR resonances assignments were obtained by two-dimensional and three-dimensional heteronuclear spectroscopy. The structure could be calculated using a set of 1015 restraints for the 147 residues of the enzyme. The overall structure is composed of a series of antiparallel beta-strands which surround two perpendicular alpha-helices. The C-terminal helix contains the HEXXH motif, which is crucial for activity. This helical arrangement and the way the histidines bind the zinc ion clearly are structurally reminiscent of the other members of the metalloprotease family, such as thermolysin or metzincins. Nevertheless, the overall arrangement of secondary and tertiary structures of peptide deformylase and the positioning of its third zinc ligand (a cysteine) are quite different from those of the other members of the family. These discrepancies, together with several biochemical differences, lead us to propose that peptide deformylase is the first example of a new class of the zinc-metalloproteases family. Studies of the interaction of peptide deformylase with either an inhibitor of the reaction or a product of the catalysed reaction, Met-Ala-Ser, as well as comparisons with the structures of other enzymes of the family, have enabled us to delineate the area corresponding to their binding site. The structural basis of the specificity of recognition of the formyl group is discussed in the context of the protease superfamily.
 ...
PMID:A new subclass of the zinc metalloproteases superfamily revealed by the solution structure of peptide deformylase. 884 3

The effect of lambda-toxin, a thermolysin-like metalloprotease of Clostridium perfringens, on the inactive epsilon-prototoxin produced by the same organism was examined. When the purified epsilon-prototoxin was incubated with the purified lambda-toxin at 37 C for 2 hr, the 32.5-kDa epsilon-prototoxin was processed into a 30.5-kDa polypeptide, as determined by SDS-polyacrylamide gel electrophoresis. A mouse lethality test showed that the treatment activated the prototoxin: the 50% lethal doses (LD50) of the prototoxin with and without lambda-toxin treatment were 110 and 70,000 ng/kg of body weight, respectively. The lethal activity of the prototoxin activated by lambda-toxin was comparable to that with trypsin plus chymotrypsin and higher than that with trypsin alone: LD50 of the prototoxin treated with trypsin and trypsin plus chymotrypsin were 320 and 65 ng/kg of body weight, respectively. The epsilon-toxin gene was cloned and sequenced. Determination of the N-terminal amino acid sequence of each activated epsilon-prototoxin revealed that lambda-toxin cleaved between the 10th and 11th amino acid residues from the N-terminus of the prototoxin, while trypsin and trypsin plus chymotrypsin cleaved between the 13th and 14th amino acid residues. The molecular weight of each activated epsilon-prototoxin was also determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The C-terminus deduced from the molecular weight is located at the 23rd or 30th amino acid residue from the C-terminus of the prototoxin, suggesting that removal of not only N-terminal but also C-terminal peptide is responsible for activation of the prototoxin.
 ...
PMID:Lambda-toxin of Clostridium perfringens activates the precursor of epsilon-toxin by releasing its N- and C-terminal peptides. 927 98


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>