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 nucleotide sequence of the pepN gene from Lactococcus lactis encoding a zinc-metallo aminopeptidase has been determined. The open reading frame of 2,538 base pairs encodes a protein with a calculated M(r) of 95,368, which agrees with the apparent M(r) of 95,000 of the gene product which was identified by polyclonal antibodies raised against the purified aminopeptidase. The amino acid sequence of the aminopeptidase of L. lactis was found to be similar to the corresponding enzymes of human, rat and mouse, with almost 30% of the residues identical. Also, a highly conserved area was identified which has similarity with the active site of thermolysin. A zinc-binding site, as well as the catalytic site for PepN, is predicted to lie within this conserved stretch. Putative promoter regions upstream of PepN were confirmed by primer extension analysis.
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PMID:Characterization of the Lactococcus lactis pepN gene encoding an aminopeptidase homologous to mammalian aminopeptidase N. 135 55

With the aim of producing an analgesia physiologically induced by endogenous opioids, several series of inhibitors of the degradation enzymes of enkephalins have been synthetized by using as a model, at the atomic level, the active site of thermolysin, a bacterial endopeptidase similar to enkephalinase. Thiorphan and retro-thiorphan are very potent inhibitors of enkephalinase (KI = 2 nM), but the retro compound is more selective, as it is unable to recognise the angiotensin conversion enzyme. Recently, a series of inhibitors containing a bidentate group were found to be capable of inhibiting the three metallopeptidases which break down the enkephalins. One of these compounds, kelatorphan, totally protects, in vitro and in vivo, Met-enkephalin from enzymatic degradation. Kelatorphan is the first complete inhibitor of enkephalin metabolism and is the only compound to possess an analgesic activity greater than that of a mixture of thiorphan and bestatin (non-specific aminopeptidase inhibitor). A tritiated derivative of kelatorphan has been used to visualise the enkephalinase in the rat brain by means of autoradiography. The enzyme has a heterogeneous distribution with a particularly high concentration in the nigro-striatal system.
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PMID:[Enkephalinase inhibitors and molecular study of the differences between active sites of enkephalinase and angiotensin-converting enzyme]. 299 52

The relationships between various properties of inhibitors of enkephalinase (membrane metalloendopeptidase, EC 3.4.24.11) i.e., enzyme inhibition, protection of endogenous enkephalins, antinociceptive activity and stimulation of locomotor activity was investigated by comparing the relative potencies of the two enantiomers of Thiorphan and acetorphan, its parenterally active prodrug. In vitro (R)- and (S)-Thiorphan were almost equipotent in inhibiting enkephalinase activity (Ki, 1.7 and 2.2 nM, respectively) or thermolysin activity (Ki, 13 and 6 microM, respectively) whereas the (R)-isomer was 44-fold less potent than the (S)-isomer on ACE activity (Ki 4800 and 110 nM, respectively). When tested on slices of rat globus pallidus in the presence of bestatin, to block the aminopeptidase pathway of enkephalin degradation, both Thiorphan enantiomers ensured a complete protection of endogenous (Met5)enkephalin released by depolarization and a suppression of the increase in the extracellular levels of Tyr-Gly-Gly, a characteristic enkephalin metabolite. These two effects occurred at EC50 values of the two enantiomers (10 nM in both cases), consistent with the idea that they were due to enkephalinase inhibition. After i.v. administration of the acetorphan enantiomers to mice, the enkephalinase activity of a rapidly prepared striatal membrane fraction was reduced in a dose-dependent manner with similar "ex vivo" ED50 values (1.0 and 0.3 mg/kg for the (R)- and (S)-isomer, respectively). In contrast the ACE activity of the same preparation was reduced in a significant manner only by (S)-acetorphan (ED50 value of 11 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enantiomers of thiorphan and acetorphan: correlation between enkephalinase inhibition, protection of endogenous enkephalins and behavioral effects. 347 50

Using ion-exchange chromatography on QAE-Sephadex A-50, affinity chromatography on DNP-hexamethylenediamine-Sepharose and gramicidin S-Sepharose and gel filtration, a metalloproteinase was isolated from the cultural fluid of L. pneumophila (strain Philadelphia-1) grown for 20 hours. The enzyme was purified 1606-fold with a 31% yield. The enzyme has a Mr of 38,000, pI approximately 4.0 and optimum of proteolytic activity at pH 6.0-7.0, 55 degrees C. The proteinase is the most stable within the pH range of 6.0-9.0. The enzyme contains one atom of zinc per molecule. The amino acid composition of metalloproteinase is close to that of thermolysin and is characterized by a high methionine content--17 residues out of 348. In the B-chain of oxidized bovine insulin the enzyme hydrolyzes the bonds precedent to the amino groups of leucine, phenylalanine and tyrosine. The enzyme is inhibited by chelating agents--Na2-EDTA and o-phenanthroline as well as by diethylpyrocarbonate. The serine and thiol proteinase inhibitors do not influence the enzyme activity. Under the given conditions of cultivation metalloproteinase is the major endopeptidase produced by L. pneumophila. Thus, the proteolytic system of Legionelles is characterized by the combination of metalloproteinase and the earlier described phenylalanine aminopeptidase.
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PMID:[Extracellular metalloproteinase from Legionella pneumophila]. 366 68

L-Leucinthiol, a synthetic derivative of mercaptoethylamine with a hydrophobic side chain, was recently reported to be a potent inhibitor of microsomal aminopeptidase. The structural features necessary for interaction of mercaptoamines with this enzyme have now been explored more systematically. Optimal binding requires a primary amine linked to the mercapto group via two carbon atoms. Only a substituent with L-configuration at the 1 position increased the affinity toward the enzyme. The high degree of specificity and other evidence suggest that the mode of binding of these inhibitors is similar to that of substrates. Comparison of leucinthiol with other amino compounds suggest that the mercapto group makes a much greater contribution to the binding than the hydrophobic side chain. L-Leucinthiol is fairly specific for aminopeptidase although some inhibition of thermolysin and carboxypeptidase A is observed.
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PMID:Structural requirements for specific inhibition of microsomal aminopeptidase by mercaptoamines. 400 71

A scheme based on the zinc binding site [1992, FEBS Lett. 312, 110-114] has been extended to classify zinc metalloproteases into distinct families. The gluzincins, defined by the HEXXH motif and a glutamic acid as the third zinc ligand, include the thermolysin, endopeptidase-24.11, aminopeptidase, angiotensin converting enzyme, endopeptidase-24.15, and tetanus and botulinum neurotoxin families. The metzincins, defined by the HEXXH motif, a histidine as the third zinc ligand and a Met-turn, include the astacin, serralysin, reprolysin and matrixin families. The inverted zincin motif, HXXEH, defines the inverzincin family of insulin-degrading enzymes, the HXXE motif defines the carboxypeptidase family, and the HXH motif DD-carboxypeptidase.
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PMID:Families of zinc metalloproteases. 795 88

Single-chain urokinase-type plasminogen activator (scu-PA) is inactivated by thrombin, which cleaves the peptide bond between Arg156 and Phe157. In a search for potential activators of thrombin-cleaved two-chain urokinase-type plasminogen activator (tcu-PA/T), we found that the lysosomal aminopeptidase dipeptidyl-peptidase I or cathepsin C efficiently activates tcu-PA/T. Cathepsin C was as active towards tcu-PA/T as the bacterial proteinase thermolysin and about 300-times more active than plasmin. The activation by cathepsin C proceeded in a concentration-dependent and time-dependent manner with a pH optimum between 5 and 7. Furthermore, the effect of cathepsin C was inhibited by cystatin and stimulated by cysteine, typical for the action of a thiol proteinase. As no degradation of the tcu-PA/T molecule by cathepsin C was visible on SDS/PAGE, we suggest that activation of tcu-PA/T occurs by cleavage between Lys158-Ile159 and removal of the two N-terminal amino acid residues (Phe157-Lys158) of the B chain of tcu-PA/T. We conclude that both thrombin and dipeptidyl-peptidases like cathepsin C might play a regulatory role in the plasminogen-plasmin system by inactivating scu-PA and activating tcu-PA/T, respectively.
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PMID:Activation of thrombin-inactivated single-chain urokinase-type plasminogen activator by dipeptidyl peptidase I (cathepsin C). 805 19

Peptides inhibitory to the 70-kDa endopeptidase (PepO) from the cytoplasm of Lactococcus lactis ssp. lactis MG1363 were isolated from the supernatant (pH 4.6) of chymosin, tryptic and alpha-chymotryptic hydrolysates of beta-casein (beta-CN) by reversed-phase HPLC and identified by sequencing and mass spectrometry. Chymosin released beta-CN f193-209, kinetic constant (Ki) of which for inhibition of PepO was 60 microM. This peptide also inhibited (Ki = 1700 microM) the 95-kDa aminopeptidase (PepN) from L. lactis ssp. lactis MG 1363. Trypsin released two PepO-inhibitory peptides: one, beta-CN f69-97, was not degradable by PepO (Ki = 4.7 microM), while the other, beta-CN f141-163, was degradable by PepO but competitively inhibited hydrolysis of methionine enkephalin by PepO. A peptide, beta-CN f69-84, which inhibited PepO with a Ki of 8.1 microM, was isolated from the alpha-chymotryptic hydrolysate. Peptides released from beta-CN by trypsin or chymotrypsin had very little inhibitory activity against PepN. PepO degraded beta-CN f193-209 very slowly compared with the hydrolysis of methionine enkephalin. All four inhibitory peptides (beta-CN f193-209, f69-97, f69-84, f141-163) were readily degraded by thermolysin.
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PMID:Peptides inhibitory to endopeptidase and aminopeptidase from Lactococcus lactis ssp. lactis MG1363, released from bovine beta-casein by chymosin, trypsin or chymotrypsin. 863 36

Statistically significant charge clusters (basic, acidic, or of mixed charge) in tertiary protein structures are identified by new methods from a large representative collection of protein structures. About 10% of protein structures show at least one charge cluster, mostly of mixed type involving about equally anionic and cationic residues. Positive charge clusters are very rare. Negative (or histidine-acidic) charge clusters often coordinate calcium, or magnesium or zinc ions [e.g., thermolysin (PDB code: 3tln), mannose-binding protein (2msb), aminopeptidase (1amp)]. Mixed-charge clusters are prominent at interchain contacts where they stabilize quaternary protein formation [e.g., glutathione S-transferase (2gst), catalase (8act), and fructose-1,6-bisphosphate aldolase (1fba)]. They are also involved in protein-protein interaction and in substrate binding. For example, the mixed-charge cluster of aspartate carbamoyl-transferase (8atc) envelops the aspartate carbonyl substrate in a flexible manner (alternating tense and relaxed states) where charge associations can vary from weak to strong. Other proteins with charge clusters include the P450 cytochrome family (BM-3, Terp, Cam), several flavocytochromes, neuraminidase, hemagglutinin, the photosynthetic reaction center, and annexin. In each case in Table 2 we discuss the possible role of the charge clusters with respect to protein structure and function.
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PMID:Clusters of charged residues in protein three-dimensional structures. 871 Aug 74

Two series of compounds synthesized as specific matrix metalloproteinase (MMP) inhibitors have been evaluated for their inhibition of non-MMPs. In a series of substituted succinyl hydroxamic acids, some were found to be significant (IC50 < 1 microM) inhibitors of leucine (microsomal) aminopeptidase, neprilysin (3.4.24.11), and thermolysin. Macrocyclic compounds in which the alpha carbon of the succinyl hydroxamate is linked to the side chain of the P2' amino acid were found to be good inhibitors of aminopeptidase, but not of neprilysin or thermolysin. Compounds of neither series were found to be significant inhibitors of angiotensin converting enzyme or carboxypeptidase A.
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PMID:Evaluation of the inhibition of other metalloproteinases by matrix metalloproteinase inhibitors. 1053 76


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