Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of alpha-chymotrypsin and alpha-lytic protease with chloro(2,2':6',2''-terpyridine)platinum(II), [Pt(trpy)Cl]+, results in attachment of Pt(trpy)2+ tags at both His 57 and His 40 in the former and His 57 in the latter. The [Pt(trpy)His]2+ chromophores are readily detected and quantitated owing to their characteristic, strong UV absorption. Although the tagging of His 57 modifies the catalytic triad (Ser 195, His 57, and Asp 102) and disrupts the charge relay, the platinated enzymes retain significant esterase and amidase activity for both specific and nonspecific substrates. Unlike suicide inhibitors, which inactivate the enzymes by filling the active site and imitating the tetrahedral intermediate, [Pt(trpy)Cl]+ reacts with a particular amino acid and permits binding of substrates. The kinetic constants for the following are reported: two esters and two amides with alpha-chymotrypsin and an amide with alpha-lytic protease. The kcat values are between 1 and 25% of, and the Km values are a little higher than, the corresponding values for the native enzymes. The catalytic activity is not due to the native enzymes, trypsin, or some zinc-containing protease. Activities of the native and of the platinated alpha-chymotrypsin depend similarly on pH although the pKa of His 57 is raised to 9.7 upon platination. The platinated enzymes undergo autodigestion slower than do the native enzymes. Because the Pt(trpy)2+ tags are noninvasive, stable, and yet easily removable by thiourea, [Pt(trpy)Cl]+ may be used to retard autodigestion of stored proteolytic enzymes.
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PMID:Catalytic activity of the serine proteases alpha-chymotrypsin and alpha-lytic protease tagged at the active site with a (terpyridine)platinum(II) chromophore. 222 78

5,6-Dihydropyrimidine amidohydrolase was isolated from an acetone powder of calf liver and purified to homogeneity. Purification made use of heat treatment, ammonium sulfate fractionation and chromatography on Chelating Sepharose and DEAE-Sepharose with 44% recovery of total activity. The native enzyme has a molecular mass of 217 kDa consisting of four subunits with a molecular mass of 54 kDa each. The amidohydrolase is a metalloenzyme containing one zinc atom/subunit. The enzyme can slowly be inactivated by chelating agents. The kinetic parameters for substrates, 5,6-dihydrouracil, 5,6-dihydrothymine and glutarimide were determined. From log Vmax/KM data, a pKa of 7.6 could be calculated suggesting the formation of a zinc-bound hydroxyl ion which carries out the nucleophilic attack on the C-4 of dihydrouracil.
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PMID:Purification and properties of 5,6-dihydropyrimidine amidohydrolase from calf liver. 271 93

Aminoacylase I from porcine kidney (EC 3.5.1.14) contains seven cysteine residues per subunit. Three sulfhydryl groups are accessible to modification by 4-hydroxymercuribenzoate (p-MB). The kinetics of the reaction suggest that only one of these groups affects acylase activity when modified by p-MB. Its reaction rate increases 2-3-fold when the essential metal ion of aminoacylase is removed. Modification of metal-free apoenzyme by N-ethylmaleimide (NEM) abolishes its activity without impairing Zn2+ binding. This indicates that the sulfhydryl group reacting with NEM is not directly coordinated to the metal. DTNB (5,5'-Dithio-bis(2-nitrobenzoate), Ellman's reagent) also modifies three sulfhydryl groups per subunit. In this case, the reactivities of native aminoacylase and apoenzyme are not significantly different. N-Hydroxy-2-aminobutyrate, a strong aminoacylase inhibitor, substantially increases the reactivity of the slowest reacting sulfhydryl in both native enzyme and metal-free aminoacylase. It appears that binding of the inhibitor or removal of the metal ion induces conformational changes of the amino-acylase active site that render a buried sulfhydryl group more accessible to modification.
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PMID:Reactivities of sulfhydryl groups in native and metal-free aminoacylase I. 277 87

A new purification procedure involving five column-chromatography steps is described for dihydro-orotase (L-5,6-dihydro-orotate amidohydrolase, EC 3.5.2.3) from Clostridium oroticum (A.T.C.C. 25750). The native purified enzyme is a dimer of Mr 102 000 and contains 4.0 +/- 0.3 g-atoms of zinc/mol of dimer. These observations agree with those reported previously [Taylor, Taylor, Balch & Gilchrist (1976) J. Bacteriol. 127, 863-873]. It is conclusively demonstrated that dihydro-orotase is a zinc metalloenzyme. Zinc is reversibly removed by treatment with chelators in phosphate buffer at pH 6.5, as demonstrated by atomic absorption spectrophotometry and decrease of enzyme activity. The specific activity is linearly dependent on zinc content. Addition of ZnSO4 to the chelator-treated enzyme results in regain of the normal complement of zinc and enzyme activity. Kinetic properties of the reconstituted enzyme are indistinguishable from those of the native enzyme. The amino acid composition of the homogeneous enzyme suggests that the zinc atoms occupy different environments.
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PMID:Dihydro-orotase from Clostridium oroticum. Purification and reversible removal of essential zinc. 286 18

During the course of investigations on the catabolism of acetylpolyamines by microorganisms, we found that acetylpolyamine amidohydrolase was produced by Mycoplana bullata FERM BP-1845 and isolated the enzyme from the cell-free extract in crystalline form. The enzyme had an apparent molecular weight of 67 kDa and was composed of two identical subunits. The enzyme activity was inhibited by o-oxyquinoline and the crystalline enzyme contained one zinc atom per each subunit. The enzyme had an optimal pH around 8.0 with acetylputrescine as substrate and showed broad substrate specificity and high affinity towards various acetylpolyamines, such as acetylputrescine, acetylcadaverine, acetylspermidine, and acetylspermine.
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PMID:Crystallization and some properties of acetylpolyamine amidohydrolase from Mycoplana bullata. 320 20

Chromatography on phosphocellulose P-11 under conditions different from those applicable for deaminases specific to 5' AMP resulted in homogeneous preparation of snail foot muscle enzyme. Snail deaminase is a tetramer with molecular weight of 240,000, composed of four apparently identical subunits. Its amino acid composition is remarkably different from deaminases of higher animals, it was not inhibited by EDTA, but zinc became inhibitory to the snail enzyme. Unlike deaminases specific to 5' AMP, nonspecific deaminase is not a zinc-containing enzyme. It was adopted further for the preparation of hypoxanthine derivatives of adenosine-containing nucleotides such as NAD, NADH, AMP-P(NH)P, AMP, ADP and ATP.
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PMID:Nonspecific snail muscle adenylate deaminase: simplified purification, characterization and use for the preparation of deamino derivatives of NAD, NADH and AMP-P(NH)P. 380 47

Dihydroorotase (4,5-L-dihydroorotate amidohydrolase (EC 3.5.2.3], which catalyzes the reversible cyclization of N-carbamyl-L-aspartate to dihydro-L-orotate, has been purified to homogeneity from an over-producing strain of Escherichia coli. Treatment of 70 g of frozen cell paste produces about 7 mg of pure enzyme, a yield of about 35%. The native molecular weight, determined by equilibrium sedimentation, is 80,900 +/- 4,300. The subunit molecular weight, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is 38,400 +/- 2,600, and by amino acid analysis is 41,000. The enzyme is thus a dimer and contains 0.95 +/- 0.08 tightly bound zinc atoms per subunit when isolated by the described procedure, which would remove any loosely bound metal ions. Isoelectric focusing under native conditions yields a major species at isoelectric point 4.97 +/- 0.27 and a minor species at 5.26 +/- 0.27; dihydroorotase activity is proportionately associated with both bands. The enzyme has a partial specific volume of 0.737 ml/g calculated from the amino acid composition and a specific absorption at 278 nm of 0.638 for a 1 mg/ml solution. At 30 degrees C, the Michaelis constant and kcat for dihydro-DL-orotate (at pH 8.0) are 0.0756 mM and 127 s-1, respectively; for N-carbamyl-DL-aspartate (at pH 5.80), they are 1.07 mM and 195 s-1.
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PMID:Dihydroorotase from Escherichia coli. Purification and characterization. 614 52

An intracellular aminopeptidase (alpha-aminoacyl-peptide hydrolase (cytosol), EC 3.4.11.1) isolated from cell extracts of Lactobacillus acidophilus R-26 was purified 634-fold to homogeneity. This enzyme, which was responsible for all of the N-terminal exopeptidase and amidase activities observed in crude extracts, had no detectable endopeptidase or esterase activity. Although a broad range of L-amino acid peptide, amide and p-nitroanilide derivatives possessing free alpha-amino termini are attacked, the enzyme favored substrates with hydrophobic N-terminal R groups. The native enzyme, which was found to be a tetramer of molecular weight 156000, contained 4 mol of tightly bound Zn2+. The catalytically inactive native zinc metalloenzyme was capable of being activated by either Zn2+, Co2+, Ni2+ or Mn2+. The shape of the log Vmax versus pH plot indicates that two active-center ionizable groups (pKES1 = 5.80; pKES2 = 8.00) may be involved in catalysis. Methylene-blue-sensitized photooxidation of the enzyme resulted in the complete loss of activity, while L-leucine, a competitive inhibitor, partially protected against this inactivation. Amino-acid analysis indicated that this photooxidative loss of activity corresponds to the modification of one histidine residue per monomer of protein.
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PMID:Isolation and characterization of an aminopeptidase from Lactobacillus acidophilus R-26. 643 50

A new procedure for the isolation of highly purified acylamino acid amidohydrolase from hog kidney is described which allows the preparation of the enzyme with a recovery of about 45%, a 200 fold purification and a spec. activity of 350-500 U. The essential Zn2+ of the enzyme was exchanged for Co2+, Ni2+, Mn2+ and Cd2+, and the kinetic parameters KM, kcat and kcat/KM of the different enzyme species for a series of acetyl-L-amino acids were determined.
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PMID:[New isolation procedure for swine kidney acylase. Kinetics of Co2+, Mn2+, Ni2+ and Cd2+-enzymes]. 651 35

1. Penicillin amidase from Proteus rettgeri was purified 580-fold by a four-step chromatographic procedure. Titration with phenylmethanesulphonyl fluoride showed that the purified preparation contains 53% of the enzyme. 2. The molecular weight of the amidase was found to be 65.000. The enzyme is strongly inhibited by N-bromosuccinimide and zinc ions. It hydrolyses penicillins, cephalosporins and some synthetic substrates, and in addition it catalyses synthesis of ampicillin from methyl ester of phenylglycine and 6-aminopenicillanic acid. 3. The immobilized amidase obtained by copolymerization of the chemically modified enzyme with acrylamide was applied for preparative hydrolysis of benzylpenicillin.
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PMID:Penicillin amidase from Proteus rettgeri. 680 83


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