Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two new methods of activation were developed to graft enzymes on collegen films. They involved chemical modifications of surface groups of collagen either by Woodward's reagent "K" or by EDC, a water-soluble derivative of carbodiimide. EDC was a better coupling agent and a detailed study was conducted with this agent. It could be used either in a global method of activation and coupling, or in a two-step procedure of activation of collagen, followed by spontaneous coupling of enzyme. All enzymes tested were successfully bound: malate dehydrogenase, lactate dehydrogenase, aspartate aminotransferase, urease, creatine kinase, hexokinase. The influence on the yield of grafted enzyme, of pretreatment of films, time and temperature of EDC activation, concentration of EDC and enzyme, protecting agents was studied. Stability of enzyme activity on storage was greatly increased after grafting. A co-grafted dual system creatine kinase/heoxkinase, was achieved which exhibited a good efficiency. A striking renaturing process at 0-4degreesC after thermal denaturation, was observed with hexokinase.
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PMID:Grafting of enzymes on collagen films using Woodward's reagent "K" and a water-soluble carbodiimide derivative. 95 53

Artificial cells containing leucine dehydrogenase (EC 1.4.1.9), alcohol dehydrogenase (EC 1.1.1.1; or glucose dehydrogenase, EC 1.1.1.47; or lactic dehydrogenase, EC 1.1.1.27; or malic dehydrogenase, EC 1.1.1.37), urease (EC 3.5.1.5) and dextran-NAD+ were prepared. Ammonia or urea could be converted into L-leucine, L-valine and L-isoleucine using artificial cells with four different multienzyme systems.
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PMID:Conversion of urea or ammonia into essential amino acids (L-leucine, L-valine, and L-isoleucine) using multienzyme systems and NADH-dextran immobilised in artificial cells. 344 45

Cytoplasmic fractions from species of the Mollicutes genera Entomoplasma, Mesoplasma, Mycoplasma, and Acholeplasma were assayed for NADH oxidase (NADH ox), ATP- and PPi-dependent phosphofructokinase (PFK), ATP- and PPi-dependent deoxyguanosine kinase (dGUOK), thymidine kinase (TK), TMP kinase (TMPK), glucose-6-phosphate dehydrogenase (G6Pde), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoenolpyruvate carboxylase, hypoxanthine-guanine phosphoribosyl transferase, dUTPase, and uracil-DNA glycosylase (UNG) activities. Membrane fractions were also examined for NADH ox activity. These activities were used as indicators of the presence and relative activities of major Mollicutes metabolic and DNA repair pathways. This was the first study to determine the presence of these enzymes in members of the genera Entomoplasma and Mesoplasma. Using the data obtained, we constructed a preliminary scheme for distinguishing genera of the class Mollicutes on the basis of the results of signature functional enzyme assays. This scheme includes phylogenetic relationships deduced from rRNA analyses, but is more informative with respect to metabolic potential. The criteria used include the presence of PPi-dependent PFK, urease, dUTPase, and dGUOK activities. Entomoplasma ellychniae ELCN-1T (T = type strain), Entomoplasma melaleucae M-1T, Mesoplasma seiffertii F7T, Mesoplasma entomophilum TACT, Mesoplasma florum L1T, Mycoplasma fermentans PG18T, and Acholeplasma multilocale PN525T were similar in most respects. NADH ox activity was localized in the cytoplasm of these organisms. These strains had ATP-dependent PFK, MDH, LDH, ATP- and PPi-dependent dGUOK, and UNG activities, but not dUTPase or G6Pde activities. In contrast, Acholeplasma equifetale C112T, Acholeplasma oculi 19LT, Acholeplasma hippikon C1T, Acholeplasma modicum PG49T, and Acholeplasma morum 72-043T had membrane-localized NADH ox activity, PPi-dependent PFK, G6Pde, and dUTPase activities, and significantly lower MDH and LDH activities and exhibited a faster rate with PPi than with ATP in the dGUOK reaction. All of the members of the Mollicutes tested had hypoxanthine-guanine phosphoribosyl transferase, phosphoenolpyruvate carboxylase, and (except for Mesoplasma entomophilum TAC(T)) UNG activities. All of the Acholeplasma strains except Acholeplasma multilocale PN525T had TK, TMPK, and UNG activities. Mesoplasma entomophilum TAC(T) was distinguished by having no detectable dUTPase, UNG, TK, and TMPK activities, indicating that there is a severe restriction in or an absence of a synthetic route to dTTP. Our data also suggest that A. multilocale PN525T is a member of an unrecognized metabolic subgroup of the genus Acholeplasma or is not an Acholeplasma strain.
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PMID:Comparative metabolism of Mesoplasma, Entomoplasma, Mycoplasma, and Acholeplasma. 886 14

Thirty-one urease-positive thermophilic Campylobacter (UPTC) isolates, including three reference strains (NCTC12892, NCTC12895 and NCTC12896), and three Campylobacter lari isolates, which were isolated from several countries and sources, were compared genotypically by using multilocus enzyme electrophoresis (MLEE). We examined allelic variation around seven enzyme loci, including the adenylate kinase, alkaline phosphatase, catalase, fumarase, malic enzyme, malate dehydrogenase, and L-phenylalanyl-L-leucine peptidase loci. MLEE typing revealed the presence of 23 different electrophoretic types (ETs) among the 31 UPTC isolates, and 14 isolates shared six electrophoretic profiles. Three different ETs were identified for the three C. lari isolates examined, and no ETs were shared by UPTC and C. lari isolates. Quantitative analyses were subsequently performed by using allelic variation data, and the results demonstrated that the mean genetic diversity was 0.655. In conclusion, MLEE demonstrated that the UPTC isolates examined are genetically hypervariable and form a cluster separate from the C. lari cluster.
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PMID:Characterization of urease-positive thermophilic Campylobacter subspecies by multilocus enzyme electrophoresis typing. 1278 30

In vitro toxic effects of sulfonylurea herbicides (thifensulfuron-methyl and metsulfuron-methyl) were evaluated according to a new protocol. Physiological conditions were reproduced in order to boost toxicovigilance. Sulfonylureas and their hydrolysis products were added to biological substrates such as urea, alanine, aspartic acid, alpha-ketoglutarate, oxaloacetate, pyruvate and then incubated with some specific enzymes. Addition of these sulfonylureas and their degradation products did not significantly change the enzymatic activity of the urease, aspartate-aminotransferase, glutamate dehydrogenase, malate dehydrogenase and lactate dehydrogenase. However, the acid hydrolysis products inhibited up to 95% of the activity of the alanine-aminotransferase at low concentrations (0.27 micromol L(-1)). Inhibition did not affect the mitochondrial aspartate-aminotransferase.
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PMID:Toxicovigilance: new biochemical tool used in sulfonylurea herbicides toxicology studies. 1476 45

Chaperonins suppress the denaturation of proteins and promote protein folding in vivo. Because hyperthermophilic chaperonins are expected to be used as a stabilizer for proteins, the effects of a group II chaperonin from a hyperthermophilic archaeum, Thermococcus strain KS-1 (T. KS-1 cpn), on the stabilization of mesophilic and thermophilic free enzymes and an enzyme co-immobilized with T. KS-1 cpn were studied. T. KS-1 cpn prevented the thermal inactivation of yeast alcohol dehydrogenase (ADH), jack bean urease, and Thermus flavus malate dehydrogenase (MDH) at high temperatures. T. KS-1 cpn also improved the long-term stability of ADH at lower temperatures. Moreover, the residual ADH activity of ADH co-entrapped with T. KS-1 cpn was improved and maintained at a higher level than that of the entrapped ADH without chaperonin. T. KS-1 cpn is useful for the stabilization of free and immobilized enzymes and applicable to various fields of biotechnology.
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PMID:Stabilization of free and immobilized enzymes using hyperthermophilic chaperonin. 1656 8

We prepared artificial cells each containing leucine dehydrogenase (EC 1.4.1.9), urease (EC 3.5.1.5), soluble dextran-NAD(+), and one of the following coenzyme regenerating dehydrogenases: glucose dehydrogenase (EC 1.1.1.47); yeast alcohol dehydrogenase (EC 1.1.1.1); malate dehydrogenase (EC 1.1.1.37); or lactate dehydrogenase (EC 1.1.1.27). Artificial cells were packed in small columns. L-Leucine, L-valine, and L-isoleucine were continuously produced with simultaneous dextran-NADH regeneration. The maximum production ratios depended on the coenzyme regenerating systems used: 83-93% for D-glucose and glucose dehydrogenase system; 90% for ethanol and yeast alcohol dehydrogenase system; 45-55% for L-malate and malate dehydrogenase system; and 64-78% for L-lactate and lactate dehydrogenase system. Kinetic experiments were also carried out. The apparent K(m) values are as follows: 0.33 mM for alpha-ketoisocaproate (KIC); 0.51 mM for alpha-ketoisovalerate (KIV); 0.58 mM for DL-alpha-keto-beta-methyl-n-valerate (KMV); 3.52 mM for urea; 27.82 mM for D-glucose; 3.89 mM for ethanol; 3.02 mM for L-malate; and 16.67 mM for L-lactate. Kinetic analysis showed that KIC, KIV, and KMV were all competitive inhibitors in the reactions catalyzed by leucine dehydrogenase. Their inhibitor constants were the corresponding K(m) values.
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PMID:Production of essential L-branched-chain amino acids in bioreactors containing artificial cells immobilized multienzyme systems and dextran-NAD+. 1859 77

Enzymic activities have been measured in cell-free extracts from nitrogen-starved cultures ofAnkistrodesmus braunii. During ten hours of nitrogenstarvation the activities of the enzymes nitrite reductase (E.C.1.6.6.4), glutamic dehydrogenase (E.C.1.4.1.4), glutamine synthetase (E.C.6.3.1.2) and urea amidolyase (E.C.3.5.1.5) were derepressed while the activities of the enzymes malate dehydrogenase (E.C.1.1.1.37) and hexokinase (E.C.2.7.1.1) remained more or less unchanged. In contrast, the photosynthetic capacity of the nitrogen-starved cultures declined rapidly and accompanying this decline were losses in the activities of ribulose diphosphate carboxylase (E.C.4.1.1.39) and triose phosphate-NADP-dehydrogenase (E.C.1.2.1.13).
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PMID:Some effects of nitrogen-starvation on nitrogen and carbohydrate metabolism inAnkistrodesmus braunii. 2442 51