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)

Semipermeable nylon-polyethylenimine artificial cells containing leucine dehydrogenase (EC 1.4.1.9), alcohol dehydrogenase (EC 1.1.1.1), urease (EC 3.5.1.5), and dextran-NAD+ were prepared. Artificial cells could convert ammonia or urea into L-leucine, L-valine, and L-isoleucine. For batch conversion in 20.0 mM of ammonium acetate substrate solutions, in 2 h 0.2 ml of artificial cells could produce 4.48 mumol of L-leucine, 9.98 mumol of L-valine, or 5.96 mumol of L-isoleucine. The corresponding conversion ratios were 22.4, 49.9, and 29.8%. In 20.0 mM of urea substrate solutions, 13.71 mumol of L-leucine, 16.12 mumol of L-valine, or 13.44 mumol of L-isoleucine was produced and the conversion ratios were 68.6, 80.6, and 67.2%. The substrate specificity of leucine dehydrogenase for the reductive amination was determined. Of the three branched-chain amino acids produced, the production rates of L-valine were the highest. The apparent Km values were as follows: 0.32 mM for alpha-ketoisocaproate, 1.63 mM for alpha-ketoisovalerate, and 0.73 mM for Dl-alpha-keto-beta-methyl-n-valerate. The leucine dehydrogenase multienzyme system had a good storage stability. It retained 72.0% of the original activity with artificial cells were stored at 4 degrees C for 6 weeks. The optimum conversion pH and temperature were 8.5-9.0 and 35-40 degrees C. The effects of urea and ammonium salts on conversion rate were also studied. The relative activities in ammonium salts solutions were 45.1-75.9% of those in urea solutions.
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PMID:Conversion of ammonia or urea into essential amino acids, L-leucine, L-valine, and L-isoleucine, using artificial cells containing an immobilized multienzyme system and dextran-NAD+. 2. Yeast alcohol dehydrogenase for coenzyme recycling. 169 39

A multienzyme system consisting of leucine dehydrogenase (EC 1.4.1.9), L-lactic dehydrogenase (EC 1.1.1.27), urease (EC 3.5.1.5), and dextran-NAD+ was microencapsulated within artificial cells. This system could convert ammonia and urea into essential amino acids, L-leucine, L-valine, and L-isoleucine. L-lactate acted as a cosubstrate for the regeneration of dextran-NADH. Greater concentrations of L-lactate favored the higher conversion ratios. The effects of ammonium salts and urea on reaction rate were also studied. The relative reaction rates in ammonium salts solutions were 44.6-78.8% of those in urea solutions. More than 90% of the original activity was retained when artificial cells were kept at 4 degrees C for 6 wk.
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PMID:Conversion of ammonia or urea into essential amino acids, L-leucine, L-valine, and L-isoleucine using artificial cells containing an immobilized multienzyme system and dextran-NAD. L-lactic dehydrogenase for coenzyme recycling. 170 78

Artificial cells containing glucose dehydrogenase (EC 1.1.1.47), leucine dehydrogenase (EC 1.4.1.9), 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 with artificial cells. Low-specific-activity glucose dehydrogenase could effectively regenerate dextran-NADH, which was recycled at a rate of 0.4 to 0.5 cycle per minute under reaction conditions. The effects of ammonium salts and urea on the conversion rate for the leucine dehydrogenase multienzyme system were also studied. The relative activities in ammonium salts solutions were 40 to 70% of those in urea solutions.
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PMID:Conversion of ammonia or urea into L-leucine, L-valine, and L-isoleucine using artificial cells containing an immobilized multienzyme system and dextran-NAD+. Glucose dehydrogenase for co-factor recycling. 245 27

The nucleotide sequences of the complete set of tRNA species in Mycoplasma capricolum, a derivative of Gram-positive eubacteria, have been determined. This bacterium represents the first genetic system in which the sequences of all the tRNA species have been determined at the RNA level. There are 29 tRNA species: three for Leu, two each for Arg, Ile, Lys, Met, Ser, Thr and Trp, and one each for the other 12 amino acids as judged from aminoacylation and the anticodon nucleotide sequences. The number of tRNA species is the smallest among all known genetic systems except for mitochondria. The tRNA anticodon sequences have revealed several features characteristic of M. capricolum. (1) There is only one tRNA species each for Ala, Gly, Leu, Pro, Ser and Val family boxes (4-codon boxes), and these tRNAs all have an unmodified U residue at the first position of the anticodon. (2) There are two tRNAThr species having anticodons UGU and AGU; the first positions of these anticodons are unmodified. (3) There is only one tRNA with anticodon ICG in the Arg family box (CGN); this tRNA can translate codons CGU, CGC and CGA. No tRNA capable of translating codon CGG has been detected, suggesting that CGG is an unassigned codon in this bacterium. (4) A tRNATrp with anticodon UCA is present, and reads codon UGA as Trp. On the basis of these and other observations, novel codon recognition patterns in M. capricolum are proposed. A comparatively small total, 13, of modified nucleosides is contained in all M. capricolum tRNAs. The 5' end nucleoside of the T psi C-loop (position 54) of all tRNAs is uridine, not modified to ribothymidine. The anticodon composition, and hence codon recognition patterns, of M. capricolum tRNAs resemble those of mitochondrial tRNAs.
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PMID:Codon recognition patterns as deduced from sequences of the complete set of transfer RNA species in Mycoplasma capricolum. Resemblance to mitochondria. 247 13

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

To examine the rate-of-living theory, age-related changes in amino acid pool sizes were investigated in the adult silkmoth, Bombyx mori, reared at low and high temperature. At either temperature concentrations of free amino acids contained in silkmoths revealed a great sexual difference. Those in females were generally much higher than in males and the former changed much more dynamically than the latter. Major amino acids or ninhydrin-positive compounds inclusive of some essential amino acids such as Leu, Ile, Val, Thr, Arg, Phe, Met, Ala, Tyr, Gln, Aspn , Lan , Cysta , GABA and PEA accumulated in 4 degrees C-moths. However, the levels of these amino changed irregularly with advanced age. Inhibition of protein synthesis may occur generally at low temperature, while protein degradation may be promoted at high temperature. High concentrations of MSO and Tau in the moths reared at high temperature than in the normal moths suggested also catabolism of amino acids proceeding together with protein degradation at high temperature. Amino acid metabolism seems to be complicated under various temperature conditions. When reared at the optimal temperature of 25 degrees C, urea is not present in the body of the silkmoth except for a slight amount in the secreted meconium. In silkmoths reared at the higher temperature of 35 degrees C, however, an extraordinary accumulation of urea occurs accompanied by a reduction in lifespan by one half. Undoubtedly, urea is produced in this terrestrial insect, although the accumulation mechanism is not clear: in silkmoths reared at various temperatures, arginase is found, but urease is not detected. Arginase activity was found to be higher in male moths than in female moths regardless of the rearing temperature. High temperature rearing also did not induce activity and female activity never exceeded that in males at either 25 degrees C or 35 degrees C rearing. Protein degradation accelerated by rearing at high temperatures may result in increased amounts of free arginine, which could cause the active production of urea. This possibility would be a counter-argument to the rate of living theory relating to longevity and temperature. However, at least the above facts signify that an extrinsic factor influences the longevity of an animal by altering its intrinsic aging process.
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PMID:Age-related changes in amino acid pool sizes in the adult silkmoth, Bombyx mori, reared at low and high temperature; a biochemical examination of the rate-of-living theory and urea accumulation when reared at high temperature. 672 18

Helicobacter pylori (HP) produces strong urease [EC 3.5.1.5], which is considered to play a role in the pathogenesis of gastritis and peptic ulcers. Inhibitions against this enzyme have been studied with hydroxamic acid (HXA) derivatives of aliphatic or aromatic carboxylic acids, amino acids and dipeptides. A number of HXAs potently inhibited the urease (I50 values were near the order of 10(-6)M), and H-Ile-Gly-NHOH (I50 = 0.20 x 10(-6)M) was the most potent inhibitor among the derivatives. HP urease was inhibited more potently, in general, than Jack bean (JB) urease by HXAs, and a correlation between the chemical structures of HXA derivatives and their inhibitory effects on HP urease was observed, in comparison with JB urease.
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PMID:Inhibition of Helicobacter pylori urease activity by hydroxamic acid derivatives. 787 52

Urea production by cortical (CCD) and medullary (OMCD) collecting ducts of the rat kidney was measured in vitro by incubating single microdissected pieces of tubule in the presence of L-[guanido-14C]arginine (0.2 mM). The [14C]urea released from the cells was hydrolysed in presence of urease added to the incubation medium and the 14CO2 formed was trapped in KOH and counted. The effect of various amino acids (AA) on urea production was investigated by adding unlabelled AA (either in combination or singly) at concentrations close to those present in blood plasma. A mixture of 17 AA decreased urea production from [14C]arginine by 46% in CCD and by 58% in OMCD. When lysine and proline were omitted from the mixture, the inhibition was less marked (19% in CCD and 43% in OMCD, respectively). When AA were tested singly, lysine induced the larger inhibition (40% in CCD and 45% in OMCD), than ornithine and glutamine (about 15% each, in CCD and OMCD), whereas proline inhibition (7% in CCD, 10% in OMCD) was not statistically significant. Branched-chain amino acids (BCAA) in combination (leucine, isoleucine and valine) also markedly reduced urea production by CCD and OMCD. Their effect was dose dependent. Solubilization of CCD and OMCD cell membranes with Triton X-100 resulted in a twofold increase in urea production by control samples; the relative inhibition (per cent) induced by BCAA was enhanced, whereas that induced by lysine was decreased. The data suggest that, in living tubules, the inhibition obtained with lysine resulted, for a large part, from competition between lysine and arginine for cell uptake via a common membrane carrier, whereas the inhibition induced by BCAA corresponded to an effect on arginase activity itself.
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PMID:Urea production by kidney collecting ducts in vitro: effect of amino acid addition. 805 17

The urease from the ascomycetous fission yeast Schizosaccharomyces pombe was purified about 4000-fold (34% yield) to homogeneity by acetone precipitation, ammonium sulfate precipitation, DEAE-Sepharose ion-exchange column chromatography, and if required, Mono-Q ion-exchange fast protein liquid chromatography. The enzyme was intracellular and only one species of urease was detected by nondenaturing polyacrylamide gel electrophoresis (PAGE). The native enzyme had a M(r) of 212 kDa (Sepharose CL6B-200 gel filtration) and a single subunit was detected with a M(r) of 102 kDa (PAGE with sodium dodecyl sulfate). The subunit stoichiometry was not specifically determined, but the molecular mass estimations indicate that the undissociated enzyme may be a dimer of identical subunits. The specific activity was 700-800 micromols urea.min-1.mg protein-1, the optimum pH for activity was 8.0, and the Km for urea was 1.03 mM. The sequence of the amino terminus was Met-Gln-Pro-Arg-Glu-Leu-His-Lys-Leu-Thr-Leu-His-Gln-Leu-Gly-Ser-Leu-Ala and the sequence of two tryptic peptides of the enzyme were Phe-Ile-Glu-Thr-Asn-Glu-Lys and Leu-Tyr-Ala-Pro-Glu-Asn-Ser-Pro-Gly-Phe-Val-Glu-Val-Leu-Glu-Gly-Glu-Ile- Glu- Leu-Leu-Pro-Asn-Leu-Pro. The N-terminal sequence and physical and kinetic properties indicated that S. pombe urease was more like the plant enzymes than the bacterial ureases.
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PMID:Purification and characterization of urease from schizosaccharomyces pombe. 874 56

The existence of nickel (Ni) deficiency is becoming increasingly apparent in crops, especially for ureide-transporting woody perennials, but its physiological role is poorly understood. We evaluated the concentrations of ureides, amino acids, and organic acids in photosynthetic foliar tissue from Ni-sufficient (Ni-S) versus Ni-deficient (Ni-D) pecan (Carya illinoinensis [Wangenh.] K. Koch). Foliage of Ni-D pecan seedlings exhibited metabolic disruption of nitrogen metabolism via ureide catabolism, amino acid metabolism, and ornithine cycle intermediates. Disruption of ureide catabolism in Ni-D foliage resulted in accumulation of xanthine, allantoic acid, ureidoglycolate, and citrulline, but total ureides, urea concentration, and urease activity were reduced. Disruption of amino acid metabolism in Ni-D foliage resulted in accumulation of glycine, valine, isoleucine, tyrosine, tryptophan, arginine, and total free amino acids, and lower concentrations of histidine and glutamic acid. Ni deficiency also disrupted the citric acid cycle, the second stage of respiration, where Ni-D foliage contained very low levels of citrate compared to Ni-S foliage. Disruption of carbon metabolism was also via accumulation of lactic and oxalic acids. The results indicate that mouse-ear, a key morphological symptom, is likely linked to the toxic accumulation of oxalic and lactic acids in the rapidly growing tips and margins of leaflets. Our results support the role of Ni as an essential plant nutrient element. The magnitude of metabolic disruption exhibited in Ni-D pecan is evidence of the existence of unidentified physiological roles for Ni in pecan.
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PMID:Nickel deficiency disrupts metabolism of ureides, amino acids, and organic acids of young pecan foliage. 1641 14


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