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)

The substrate specificity of carboxypeptidase (F-II) purified from watermelon for various synthetic peptides and esters was examined kinetically. The enzyme showed a broad substrate specificity against various carbobenzoxy- and benzyl-dipeptides. Peptides containing glycine or proline were hydrolyzed slowly by the enzyme. Peptides containing hydrophobic amino acids were hydrolyzed rapidly. The presence of hydrophobic amino acid residues, not only at the C-terminal position but also at the second position and probably the third position from the C-terminal resulted in an increase in the rate of hydrolysis. Inhibition studies with diisopropyl flurophosphate and diastereomers of carbobenzoxy-Phe-Ala demonstrated that the peptidase and esterase activities of the enzyme are both catalyzed by the same site of the enzyme molecule, but the binding sites for peptides and esters seem not to be the same. The enzyme also had amidase activity, which was optimal at pH 7.0.
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PMID:Substrate specificity of carboxypeptidase from Watermelon. 0 3

1. Alanine inhibits rabbit muscle AMP-deaminase while aspartate, histidine and glutamate are ineffective. 2. The degree and type of inhibition of AMP-deaminase by alanine depend on pH; at pH 6.5 alanine behaves like an allosteric effector exerting a negative heterotropic effect. At pH 7.0 the inhibition is non-competitive, Ki being as high as 19 mM. 3. The probable significance of the effect of alanine on AMP-deaminase in muscle metabolism is discussed.
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PMID:Inhibition by alanine of AMP-deaminase from rabbit skeletal muscle. 0 58

The pneumococcal bacteriophage Dp-1 seems to require the activity of the N-acetylmuramic acid-L-alanine amidase of the host bacterium for the liberation of phage progeny into the medium. This conclusion is based on a series of observations indicating that the exit of progeny phage particles is prevented by conditions that specifically inhibit the activity of the pneumococcal autolysin. These inhibitory conditions are as follows: (i) growth of the bacteria on ethanolamine-containing medium; (ii) growth of the cells at pH values that inhibit penicillin-induced lysis of pneumococcal cultures and lysis in the stationary phase of growth; (iii) addition of trypsin or the autolysin-inhibitory pneumococcal Forssman antigen (lipoteichoric acid) to the growth medium before lysis; (iv) infection of an autolysin-defective pneumococcal mutant at a multiplicity of infection less than 10 (treatment of such infected mutant bacteria with wild-type autolysin from without can liberate the entrapped progeny phage particles); (v) release of phage particles and culture lysis can also be inhibited by the addition of chloramphenicol to infected cultures just before the time at which lysis would normally occur. Bacteria infected with Dp-1 under conditions nonpermissive for culture lysis and phage release secrete into the growth medium a substantial portion of their cellular Forssman antigen in the form of a macromolecular complex that has autolysin-inhibitory activity. We suggest that a phage product may trigger the bacterial autolysin by a mechanism similar to that operating during treatment of pneumococci with penicillin (Tomasz and Waks, 1975).
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PMID:Role of the pneumococcal autolysin (murein hydrolase) in the release of progeny bacteriophage and in the bacteriophage-induced lysis of the host cells. 1 29

This study demonstrates, for the first time, the autolytic enzymes associated with mycobacterial cell walls. Based on the release of radioactivity and ninhydrin-reactive material from isolated cell walls, it was shown that maximum activity occurs during the late log phase of growth and at a buffer pH of about 8.0. Chemical analyses of autolytic digests of isolated cell walls indicated that at least three autolysins are active under the conditions used. These are N-glycolylmuramic acid-L-alanine amidase, an aminopeptidase that releases L-alanine, and an endopeptidase that solubilizes and L-alanyl-D-glutamic acid dippetide. No other endopeptidase, carboxypeptidase, or glycosidase activity was detected.
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PMID:Characterization of autolysins from Mycobacterium smegmatis. 1 9

Peptidoglycan (PG) turnover in exponentially growing Neisseria gonorrhoeae RD5 type 4 was accompanied by release of soluble PG fragments into the medium. Turnover of the D-[14C]glucosamine-labeled glycan moiety and of the meso-[3H]diaminopimelic acid (DAP)-labeled peptide region occurred at similar rates (ca. 35% per generation). Turnover of D-[14C]alanine-labeled sites within the peptide side chain of PG occurred at roughly twice this rate; no turnover of L-[3H]proline-labeled protein was detected. Gel filtration of supernatants of cultures grown in the presence of labeled DAP, glucosamine, and D-alanine as described above and paper chromatography of hydrolyzed peak fractions revealed four major types of soluble PG. Two of these contained both peptide and glycan moieties and appeared to represent forms of disaccharide peptide monomers and dimers. The other two were (i) a 3H-labeled product lacking 14C and (ii) a 14C-containing product lacking 3H, which were similar in size to that expected for free tetrapeptides and free disaccharides, respectively. Together the appearance of these PG fragments and the concurrent turnover of glycan and peptide regions indicate that both glycan splitting and amidase PG hydrolase activities are involved in the turnover of PG in growing gonococci. If released during gonococcal infections, similar soluble PG fragments might influence the consequences of host-gonococcus interactions.
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PMID:Release of soluble peptidoglycan from growing gonococci: hexaminidase and amidase activities. 11 60

Protein C is a vitamin K-dependent protein, which exists in bovine plasma as a precursor of a serine protease. In this study, protein C was isolated to homogeneity from human plasma by barium citrate adsorption and elution, ammonium sulfate fractionation, DEAE-Sephadex chromatography, dextran sulfate agarose chromatography, and preparative polyacrylamide gel electrophoresis. Human protein C (M(r) = 62,000) contains 23% carbohydrate and is composed of a light chain (M(r) = 21,000) and a heavy chain (M(r) = 41,000) held together by a disulfide bond(s). The light chain has an amino-terminal sequence of Ala-Asn-Ser-Phe-Leu- and the heavy chain has an aminoterminal sequence of Asp-Pro-Glu-Asp-Gln. The residues that are identical to bovine protein C are underlined. Incubation of human protein C with human alpha-thrombin at an enzyme to substrate weight ratio of 1:50 resulted in the formation of activated protein C, an enzyme with serine amidase activity. In the activation reaction, the apparent molecular weight of the heavy chain decreased from 41,000 to 40,000 as determined by gel electrophoresis in the presence of sodium dodecyl sulfate. No apparent change in the molecular weight of the light chain was observed in the activation process. The heavy chain of human activated protein C also contains the active-site serine residue as evidenced by its ability to react with radiolabeled diisopropyl fluorophosphate. Human activated protein C markedly prolongs the kaolin-cephalin clotting time of human plasma, but not that of bovine plasma. The amidolytic and anticoagulant activities of human activated protein C were completely obviated by prior incubation of the enzyme with diisopropyl fluorophosphate. These results indicate that human protein C, like its bovine counterpart, exists in plasma as a zymogen and is converted to a serine protease by limited proteolysis with attendant anticoagulant activity.
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PMID:Human plasma protein C: isolation, characterization, and mechanism of activation by alpha-thrombin. 46 91

The N-acetymuramic acid L-alanine amidase from Bacillus subtilis (ATCC 6051) has been purified to homogeneity. It is a monomeric protein of molecular weight 50,000. The enzyme has a high affinity for homologous cell walls and once attached to a cell wall will hydrolyze the wall completely before initiating the hydrolysis of a new cell wall. The affinity of the enzyme for cell walls devoid of teichoic acid or for cell walls of Bacillus megaterium is much lower than that for B. subtilis cell walls. A second homogenous protein has been isolated from B. subtilis which specifically combines with the amidase in a 1:1 molar ratio and stimulates enzyme activity. This modifier protein has no intrinsic cell wall lytic activity. The binding of enzyme and modifier protein has a dissociation constant of 8.5 times 10-9 M in 0.1 M LiCl, pH 8.0, but the two proteins can be completely dissociated in 3 M LiCl at pH 8.0.
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PMID:Bacillus subtilis N-acetylmuramic acid L-alanine amidase. 80 7

A thermophilic bacillus growing on acetamide as both carbon and nitrogen sources produces an inducible amidase. This amidase hydrolysed the following amides in decreasing order or activity, in comparison with acetamide (1.00): propionamide (0.97), fluoroacetamide (0.84), formamide (0.35) and glycinamide (0.12). Cyanoacetamide, dimethylacetamide, dimethylformamide and urea also induced the synthesis of the amidase, but were not substrates of the enzyme. Studies with protoplasts suggest that the amidase is located in the cytoplasm. Glucose strongly inhibited amidase synthesis; and limiting nitrogen did not release this inhibition. Urea strongly inhibited amidase activity in a competitive manner; but the inhibition caused by iodoacetamide and cyanoacetamide was non-competitive. Both thioacetamide and thiourea were effective inhibitors of enzyme induction. Bacteria grown on a succinate-minimal medium exhibited a lag in amidase synthesis, which could be eliminated by decreasing the concentration of succinate. Acetate- or pyruvate-grown cultures behaved similarly, while those grown on alanine or glutamate exhibited no lag in enzyme induction. In the mutant strain E21, repression of amidase synthesis by glucose was much less evident and no lag for induction was apparent with any of the other carbon sources mentioned.
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PMID:Regulatory properties of an inducible aliphatic amidase in a thermophilic bacillus. 93 86

D-alanyl-meso-2, 6-diaminopimelic acid (D-Alanyl-meso-A2pm) endopeptidase was isolated and purified from a crude Streptomyces L-3 enzyme preparation by ion exchange chromatography and isoelectric focusing in a density gradient. During its purification, its hydrolytic activity was assayed on cell walls of Lactobacillus plantarum ATCC 8014 and soluble glycopeptides and peptides, of known chemical structures, prepared enzymatically from these cell walls. A fraction with an isoelectric point of pH 7.9 cleaved the bond between the carboxyl group of the D-alanine residue at the C-terminal in one peptide subunit and one of the two amino groups of the A2pm residue in the neighboring peptide subunit. Unlike the crude enzyme, the endopeptidase in this fraction showed no N-acetylmuramyl-L-alanine amidase, A2pm carboxyamide amidase or proteinase(s) activity and it was immunologically homogeneous.
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PMID:Isolation and purification of D-alanyl-meso-2, 6-diaminopimelic acid endopeptidase of Streptomyces L-3 enzyme using soluble substrates of known chemical structure from Lactobacillus plantarum cell wall digests. 101 17

N-Acetylmuramyl-L-alanine amidase activity was detected in Escherichia coli K 12 by usine N-acetylmuramyl-L-alanyl-gamma-D-glutamyl-(L)-meso-[3H]diaminopimelic acid as a radioactive substrate. This activity cleaves the amide bond between the residues of N-acetylmuramyl acid and L-alanine. It was readily obtained in a soluble form either by mechanical disruption of the cells or by spheroplast formation. In the latter case the release of most of the activity into the sucrose medium seems to indicate that it is either periplasmic or associated with the outer membrane of the envelope of E. coli K 12. The enzyme was purified to near homogeneity. A molecular weight of 39 000 was determined by gel filtration and confirmed by polyacrylamide gel electrophoresis. Further characterisation of this N-acetylmuramyl-L-alanine amidase activity was carried out by investigating several of its properties.
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PMID:Envelope-bound N-acetylmuramyl-L-alanine amidase of Escherichia coli K 12. Purification and properties of the enzyme. 110 8


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