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)

From mouse spinal cord homogenate, we isolated a trophic substance which reverses the post-denervation decrease in tetrodotoxin sensitivity of action potential in organ-cultured extensor digitorum longus muscle of mouse and characterized its physicochemical properties. The trophic substance was separated from macromolecules in homogenate by gel filtration on Biogel P2 column. The partially purified trophic substance was heat-stable, acid-stable and alkaline-labile. The trophic activity was destroyed by lyophilization at neutral pH but not at acidic pH. The trophic activity was abolished by incubation with pronase or leucine aminopeptidase, but not by trypsin, chymotrypsin, thermolysin or carboxypeptidase A. The trophic substance passed through an ultrafiltration membrane UM10 freely. A small part of the trophic activity passed through a UM2 or UM05, and the rest was retained on the membranes. The trophic substance adsorbed on CM-Sephadex at pH 7.2 but passed through DEAE-Sephadex at pH 8.4. These results suggest that the trophic substance regulating tetrodotoxin sensitivity of action potential in mouse skeletal muscle is a peptide with a rather low molecular weight of less than 10,000 and that while the N-terminus of the peptide is free, the C-terminus is probably blocked. This peptide differs from other trophic substances reported previously by other investigators.
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PMID:Partial purification and characterization of neutrophic substance affecting tetrodotoxin sensitivity of organ-cultured mouse muscle. 48 37

Galline, a protamine from rooster sperm nuclei, has already been separated into its components, G-I-G-VIII. The amino acid composition of the homogeneously purified fraction G-I is determined decisively to be Arg11, Ser2, Gly3, Val1 and Tyr2, and the molecular weight is 2,908 as hydrochloride. The complete amino acid sequence was deduced as follows from the results of analyses of the tryptic and chymotryptic peptides: H-Ser-Gly-Gly-Val-Arg-Arg-Arg-Arg-Tyr-Gly-Ser-Arg-Arg-Arg-Arg-Arg-Arg-Arg-Tye-OH. Another purified fraction, G-V, has the amino acid composition, Arg24, Thr1, Ser8, Gly3, Ala2, Pro2 and Tyr2 as described previously, and the molecular weight 6,274 as hydrochloride. The complete amino acid sequence was established by combining analytical results of tryptic, chymotryptic and thermolysin peptides as well as those of carboxypeptidase and leucine aminopeptidase digestion as follows: H-Ala-Arg-Tyr-Arg-Ser-Gly-Arg-Ser-Arg-Ser-Arg-Arg-Thr-Arg-Arg-Arg-Arg-Ser-Pro-Arg-Ser-Arg-Gly-Arg-Ser-Pro-Arg-Arg-Arg-Arg-Ser-Arg-Arg-Arg-Arg-Arg-Tyr-Gly-Ser-Ala-Arg-Arg-OH.
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PMID:Studies on a protamine (galline) from fowl sperm. 2. The amino acid sequences of two components of galline. 116 76

Benzoyl- and isopentenoyl phosphoric triamides (BPA and IPA) strongly inhibited urease activities from jack bean, soybean, watermelon seed, Proteus mirabilis, P. rettgeri, P. vulgaris, Mycobacterium smegmatis, and Ureaplasma urealyticum. Their I50 values (the final concentration causing 50% inhibition), independent of enzyme source, were 2-21 nM, which are about 1,000-fold lower than that of caprylohydroxamic acid, one of the most potent urease inhibitors. ATP-urea amidolyase activity was inhibited 50% by BPA at a higher concentration of 0.28 mM, but was not affected by IPA even at 1.3 mM. Thirteen kinds of hydrolases (trypsin, chymotrypsin, thermolysin, leucine aminopeptidase, papain, lipase, alpha-amylase, glucuronidase, asparaginase, arylsulfatase, alkaline phosphatase, acid phosphatase, and true cholinesterase), two oxidoreductases (catalase and alcohol dehydrogenase), three transferases (glutamic-oxaloacetic aminotransferase, gamma-glutamyl transpeptidase, and arylsulfotransferase) and two kinases (pyruvate kinase and creatine kinase) were not affected at all even at 1 mM BPA and IPA. Exceptionally, pseudo-cholinesterase from human serum was inhibited by BPA and IPA, whose I50 values were 70 nM and 10 muM, respectively, using acetylthiocholine as a substrate. These values increased to 0.55 muM and 54 muM, respectively, when acetylcholine was used as a substrate. These results show that N-acylphosphoric triamides potently and specifically inhibit urease activity at concentrations of nM order.
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PMID:Specific inhibition of urease by N-acylphosphoric triamides. 384 42

Treatment of liver plasma membranes with trypsin at low concentrations (1 to 2 microgram/mg of protein) caused at 3- to 4-fold increase in alpha-specific [3H]epinephrine binding. The change was due to an increase in the number of high affinity binding sites, with no change in the dissociation constant. With increasing trypsin concentrations, the dissociation constant was decreased and there was a progressive loss of binding. Elastase, papain, and thermolysin caused similar effects, whereas the thrombin, leucine aminopeptidase, phospholipase A2, phospholipase C, phospholipase D, and detergents did not cause an increase in [EH]epinephrine binding. The increase in epinephrine high affinity binding sites was correlated with a loss of high affinity [3H]-dihydroergocryptine binding sites which also bind [3H]epinephrine with low affinity (El-Refai, M. F., Blackmore, P. F., and Exton, J. H. (1979) J. Biol. Chem. 254, 4375-4386). Incubation of membranes with the alpha blockers dihydroergocryptine (50 nM) and phenoxybenzamine (20 nM) prior to protease treatment diminished the increase in [3H]epinephrine binding induced by trypsin (1.5 microgram/mg). The concentration dependence and time course of trypsin actions on 70 nM [3H]epinephrine binding and 10 nM [3H]dihydroergocryptine binding are consistent with a trypsin-mediated conversion of low affinity epinephrine binding sites to high affinity epinephrine binding sites.
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PMID:Effects of trypsin on binding of [3H]epinephrine and [3H]-dihydroergocryptine to rat liver plasma membranes. Evidence for interconversion of binding sites. 624 49

Transpeptidation reactions catalyzed by chymotrypsin, pepsin, leucine aminopeptidase and thermolysin have been studied in heavy oxygen water (H2 18O). The 18O incorporation into the peptide bond of transpeptidation products and into the non-hydrolyzed substrate has been measured. The rates of 18O exchange in the carboxylic groups of N-acetylphenylalanine and leucine, catalyzed by pepsin and leucine aminopeptidase, respectively, have also been determined. These rates have been compared with that of the exchange in the presence of amino compounds which reversibly form amide bonds with the above carboxyl-containing substances. The data obtained show that, in contrast to chymotrypsin, other enzymes studied do not form 'acyl-enzymes' but function by the mechanism of general-base catalysis. In other words, their catalytically active groups promote the abstraction of a proton from the water molecule, which attacks the susceptible bond of the substrate. The structure of intermediate compounds in this type of catalysis and the mechanism of the transpeptidation reaction are discussed.
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PMID:Studies on the mechanisms of action of proteolytic enzymes using heavy oxygen exchange. 679 Feb 82

The topological disposition of Wolfgram proteins (WP) and their relationship with 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in human, rat, sheep, bovine, guinea pig and chicken CNS myelin was investigated. Controlled digestion of myelin with trypsin gave a 35KDa protein band (WP-t) when electrophoresed on dodecyl sulfate-polyacrylamide gel in all species. Western blot analysis showed that the WP-t was derived from WP. WP-t was also formed when rat myelin was treated with other proteases such as kallikrein, thermolysin and leucine aminopeptidase. Staining for CNPase activity on nitrocellulose blots showed that WP-t is enzymatically active. Much of the CNPase activity remained with the membrane fraction even after treatment with high concentrations of trypsin when WP were completely hydrolysed and no protein bands with M.W > 14KDa were detected on the gels. Therefore protein fragments of WP with M.W < 14KDa may contain CNPase activity. From these results, it is suggested that the topological disposition of all the various WP is such that a 35KDa fragment is embedded in the lipid bilayer and the remaining fragment exposed at the intraperiod line in the myelin structure which may play a role in the initiation of myelinogenesis.
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PMID:Topology of Wolfgram proteins and 2', 3'-cyclic nucleotide 3'-phosphodiesterase in CNS myelin: studies with proteases. 782 62

Nitrile hydratase (NHase) from Rhodococcus sp. N-771 is a photoreactive enzyme that is inactivated by nitrosylation of the non-heme iron center and activated by photodissociation of nitric oxide (NO). To obtain structural information on the iron center, we isolated peptide complexes containing the iron center by proteolysis. When the tryptic digest of the alpha subunit isolated from the inactive form was analyzed by reversed-phase high performance liquid chromatography, the absorbance characteristic of the nitrosylated iron center was observed in the peptide fragment, Asn105-Val-Ile-Val-Cys-Ser-Leu-Cys-Ser-Cys-Thr-Ala-Trp-Pro-Ile-Leu - Gly-Leu-Pro-Pro-Thr-Trp-Tyr-Lys128. The peptide contained 0.79 mol of iron/mol of molecule as well as endogenous NO. Subsequently, by digesting the peptide with thermolysin, carboxypeptidase Y, and leucine aminopeptidase M, we found that the minimum peptide segment required for the nitrosylated iron center is the 11 amino acid residues from alphaIle107 to alphaTrp117. Furthermore, by using mass spectrometry, protein sequence, and amino acid composition analyses, we have shown that the 112th Cys residue of the alpha subunit is post-translationally oxidized to a cysteine-sulfinic acid (Cys-SO2H) in the NHase. These results indicate that the NHase from Rhodococcus sp. N-771 has a novel non-heme iron enzyme containing a cysteine-sulfinic acid in the iron center. Possible ligand residues of the iron center are discussed.
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PMID:Structure of the photoreactive iron center of the nitrile hydratase from Rhodococcus sp. N-771. Evidence of a novel post-translational modification in the cysteine ligand. 936 4