Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three homogeneous preparations of D-alanine carboxypeptidases I have been obtained from Escherichia coli strain H2143, termed enzymes IA, IB, and IC. Enzyme IA purified from the membrane after extraction with Triton X-100 appeared on sodium dodecyl sulfate gel electrophoresis to be a polypeptide doublet whose monomer molecular weights were about 32,000 and 34,000. In addition to D-alanine carboxypeptidase activity, it catalyzed a transpeptidase reaction with several substrates, bound [14C]penicillin G, had a weak penicillinase activity, but was devoid of endopeptidase activity. Enzyme IB obtained from the membrane after LiCl extraction and enzyme IC obtained from the supernatant solution were either identical or extremely similar. They were composed of a single polypeptide whose monomer molecular weight was about 41,000. In addition to carboxypeptidase activity, they catalyzed an endopeptidase reaction, had weak penicillinase activity, and had very poor transpeptidase activity, but did not bind [14C]penicillin G. Some data relating to the mechanism of catalysis by these enzymes are described. Their possible physiological role is discussed.
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PMID:Purification to homogeneity and properties of two D-alanine carboxypeptidases I From Escherichia coli. 0 91

The preparation and properties of cathepsin D from rat liver are reported. The enzyme is an endopeptidase of lysosomal origin. The molecular weight was estimated to be 49000 by sodium-dodecylsulfate electrophoresis. We did not find any dissociation into subunits under reducing conditions, in contrast to some other authors. We found the enzyme to occur in at least 4 forms with the isoelectric points 5.87, 5.65, 5.41 and 5.13. Strong -SH-blocking reagents inhibit the activity, but the most powerful and specific inhibitor was pepstatin (Ki=38 nM). The substrate specificity is discussed. There was no proof for any zymogen activation in a great number of experiments. Since the cathepsins B1, B3 and L obviously seem to play the major role in the intracellular protein breakdown within the rat liver, the main task of cathepsin D is the degradation of extracellular proteins in this organ.
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PMID:[Intracellular protein breakdown. VI. Isolation, properties and biological significance of cathepsin D from rat liver]. 0 65

1. Cathepsin L was purified from rat liver lysosomes by cell fractionation, osmotic disruption of the lysosomes in the lysosomal mitochondrial pellet, gel filtration of the lysosomal extract and chromatography on CM-Sephadex. 2. Cathepsin L is a thiol proteinase and exists in several multiple forms visible on the disc electropherogram. By polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate its molecular weight was found to be 23000-24000. The isoelectric points of the multiple forms of cathepsin L extended from pH 5.8-6.1 ascertained by analytical isoelectric focusing. 3. Using various protein substrates, cathepsin L was found to be the most active endopeptidase from rat liver lysosomes acting at pH 6-7. In contrast to cathepsin B1, its capability of hydrolyzing N-substituted derivatives of arginine is low and it does not split esters. 4. Greatest activity is obtained close to pH 5.0 with 70-90% of maximal activity at pH 4.0 and pH 6.0 and 30-40% at pH 7.0. 5. The enzyme is strongly inhibited by leupeptin and the chloromethyl ketone of tosyl-lysine. Leupeptin acts as a pseudo-irreversible inhibitor. 6. The enzyme is stable for several months at slightly acid pH values in the presence of thiol compounds in a deep-frozen state.
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PMID:Cathepsin L. A new proteinase from rat-liver lysosomes. 1 35

A simplified procedure for the purification of the extracellular protease of Pseudomonas fragi was developed. The enzyme was isolated from a derepressed mutant producing 40 times the enzyme level of the parental organism. It was collected from culture filtrates by ammonium sulfate precipitation, and it was obtained in pure form by single chromatography on a column of diethylaminoethyl cellulose. The protease had a molecular weight of 52,000 as estimated by sodium dodecyl sulfate-gel electrophoresis and had properties of a classical neutral endopeptidase with the exception of its substrate specificity. Mutants of P. fragi producing proteases of altered substrate specificities were isolated from plates containing elastin as the sole carbon source. The SP-Sephadex elution patterns of enzymes extracted from each mutant examined were complex, suggesting that either the enzyme was autodigested or several active forms could be generated from a common precursor. The substrate specificities of the mutant enzymes were different from that produced by the parental strain.
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PMID:Isolation and properties of the protease from the wild-type and mutant strains of Pseudomonas fragi. 4 39

The intrinsic effect of various beta-lactam antibiotics on the biosynthesis of peptidoglycan of Pseudomonas aeruginosa X-48 was investigated. Most of the cephalosporins and penicillins tested already at 0.5 microgram/ml strongly inhibited (a) the incorporation of nascent peptidoglycan into the detergent-insoluble fraction (greater than 75%), (b) the formation of peptide crosslinkages (greater than 60%) and (c) the activity of the DD-carboxypeptidase and partially that of the transpeptidase (approximately 90% and approximately 40% respectively). Another group of beta-lactum drugs did not inhibit incorporation into the material insoluble in sodium dodecylsulfate, the formation of peptide crosslinkages nor transpeptidase activity. They only partially inhibited the activity of the DD-carboxypeptidase--endopeptidase system (40--50% at 0.5 microgram/ml). The results obtained differ from those of Presslitz and Ray [Antimicrob, Agents Chemother. 7, 578--581 (1975)] and show some resemblance to the effects of beta-lactams on the biosynthesis of Escherichia coli peptidoglycan.
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PMID:Biosynthesis of peptidoglycan in Pseudomonas aeruginosa. 2. Mode of action of beta-lactam antibiotics. 10 30

The proteins of microvilli prepared from pig kidney were analysed by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The typical pattern stained for protein revealed five major bands, four of which also stained for carbohydrate, and about 15 minor bands. For descriptive purposes the bands were designated numerically by their apparent molecular weights (X10(-3). Well-characterized proteins were identified with four of the five major bands. Dipeptidyl peptidase IV, a serine proteinase that may be specifically labelled with di-isopropyl [32P]phosphorofluoridate, was assigned to band 130. Aminopeptidase M was assigned to band 160, though when released from the membrane by a proteinase, this protein comprises three polypeptides each of lower apparent molecular weight than the native enzyme. Neutral endopeptidase can be assigned to band 95 and actin to band 42. The fifth major band (180) is an extrinsic glycoprotein that has not been identified with any microvillus enzyme activity. These four proteins contribute 21% of the microvillus-membrane protein. Kidney microvillus actin was characterized by a variety of properties and was similar to muscle actin. A computer analysis of the gel pattern indicates that it comprises 9.0% of the microvillus protein. Myosin is not present in the microvillus, but another protein associated with band 95, with properties that distinguish it from neutral endopeptidase, was tentatively identified as alpha-actinin. Alkaline phosphatase was identified as a monomeric polypeptide with an apparent molecular weight of 80000; it is a minor protein of the microvillus and is not discernible as a discrete band in the gel pattern. These and other results permit a model of the organization of the microvillus protein to be suggested. The computer program used has been deposited as Supplementary Publication SUP 50070 (12 pages) at the British Library Lending Division, Boston Spa. Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1976) 153,5.
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PMID:Proteins of the kidney microvillus membrane. Identification of subunits after sodium dodecylsullphate/polyacrylamide-gel electrophoresis. 13 63

The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein homogeneity and compared with the exocellular DD-carboxypeptidases-transpeptidases of Streptomyces R61 and Actinomadura R39. The S. albus G enzyme, as it is isolated, occurs in two forms. Enzyme I (30% of the total amount) and enzyme II (70% of the total amount) are identical in all respects, except that, by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, enzyme I has an apparent mol. wt. (9000) that is half of that found by molecular-sieve filtration under non-denaturing conditions. Irrespective of the technique used, enzyme II has an apparent mol. wt. of about 18500.
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PMID:The exocellular DD-carboxypeptidase-endopeptidase from Streptomyces albus G. Purification and chemical properties. 74 35

Protease I, a periplasmic endopeptidase from Escherichia coli has been further purified by a modified procedure. While the purified protein consists of a single polypeptide chain of about 21000 daltons, its molecular weight in dilute salt solution was estimated to be near 43000, suggesting that the enzyme has a marked tendency to dimerize. It has only one disulphide bond and is very sensitive to urea. In agreement with previous evidence of a chymotrypsin-like specificity, hydrolytic assays of various p-nitrophenyl esters of N-substituted amino acids showed that phenylalanine and tyrosine derivatives are the best substrates for the enzyme. The Km(app) for N-benzoyloxycarbonyl-L-tyrosin-p-nitrophenyl ester at pH 7.5 In 100 mM sodium phosphate buffer at 25 degrees C was found to be 0.2 mM. In contrast to chymotrypsin, protease I is unable to hydrolyse N-acetyl-L-phenylalanine ethyl ester and its tyrosine analogue. Moreover, the enzyme appears devoid of amidase activity and exhibits a low activity upon polypeptides. At 37 degrees C, it cleaves the carboxymethylated B-chain of bovine insulin at four points: Phe25-Tyr26, Phe24-Phe25, Leu15-Tyr16 and Ser9-His10. From a detailed study of peptides bonds hydrolyzed, it was concluded that protease I has a stringent requirement for both residues forming the scissile bond, and appears to possess an extended hydrophobic binding site.
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PMID:Protease I from Escherichia coli. Some physicochemical properties and substrate specificity. 79 43

Post-proline dipeptidyl aminopeptidase (dipeptidylpeptide hydrolase, EC 3.4.14.1), also known as glycylprolyl beta-naphthylamidase or dipeptidyl aminopeptidase IV, was isolated and purified in an overall yield of 20% from autolyzed extracts of lamb kidney by CM-cellulose and column chromatography on DEAE-Sephadex and Sephadex G-200. Purified enzyme was homogeneous by disc gel electrophoresis and ultracentrifugal analysis and was most active at pH 7.8 using Gly-Pro beta-napthylamide as substrate. The Km values for Gly-Pro beta-naphthylamide and Ala-Ala beta-naphthylamide were 0.63 and 0.77 mM, respectively. The proline-containing peptides were hydrolysed more than 10-fold faster. By isoelectric focusing a pI of 4.9 was determined. The enzyme was estimated to be 230 000 +/- 15 000 by the sedimentation equilibrium method and sodium dodecyl sulfate polyacrylamide gel electrophoresis indicating that the enzyme is composed of two identical subunits with molecular weights of 115 000. It was inhibited by the active-site directed, irreversible inhibitor diisopropylphosphorofluorofluoridate. Post-proline dipeptidyl aminopeptidase, in contrast to the endopeptidase post-proline cleaving enzyme [9,10] (Walter R. (1976) Biochim. Biophys. Acta 422, 138-158, and Koida, M. and Walter, R. (1976) J. Biol. Chem. 251, 7593-7599) exhibits no endopeptidase activity. Instead it is an exopeptidase with a high specificity for NH2-terminal-free peptides containing a proline residue in the penultimate position and releases the dipeptide with proline being the COOH-terminal moiety. The name "post-proline dipeptidyl aminopeptidase" is suggested.
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PMID:Post-proline dipeptidyl aminopeptidase (dipeptidyl aminopeptidase IV) from lamb kidney. Purification and some enzymatic properties. 92 19

Dipeptidyl peptidase IV, an enzyme that releases dipeptides from substrates with N-terminal sequences of the forms X-Pro-Y or X-Ala-Y, was purified 300-fold from pig kidney cortex. The kidney is the main source of the enzyme, where it is one of the major microvillus-membrane proteins. Several other tissues contained demonstrable activity against the usual assay substrate glycylproline 2-naphthylamide. In the small intestine this activity was greatly enriched in the microvillus fraction. In all tissues examined, the activity was extremely sensitive to inhibition by di-isopropyl phosphorofluoridate (Dip-F), but relatively resistant to inhibition by phenylmethylsulphonyl fluoride. It is a serine proteinase which may be covalently labelled with [32P]Dip-F, and is the only enzyme of this class in the microvillus membrane. The apparent subunit mol.wt. estimated by sodium dodecyl-sulphate/polyacrylamide-gel electrophoresis and by titration with [32P]Dip-F was 130 000. Gel-filtration and sedimentation-equilibrium methods gave values in the region of 280 000, which is consistent with a dimeric structure, a conclusion supported by electron micrographs of the purified enzyme. Among other well-characterized serine proteinases, this enzyme is unique in its membrane location and its large subunit size. Investigation of the mode of attack of the peptidase on oligopeptides revealed that it could hydrolyse certain N-blocked peptides, e.g. Z-Gly-Pro-Leu-Gly-Pro. In this respect it is acting as an endopeptidase and as such may merit reclassification and renaming as microvillus-membrane serine peptidase.
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PMID:Dipeptidyl peptidase IV, a kidney brush-border serine peptidase. 96 53


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