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:6.3.4.6 (urease)
7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

The API STAPH-IDENT system was compared with conventional methods for the identification of 14 Staphylococcus species. Conventional methods included the Kloos and Schleifer simplified scheme and DNA-DNA hybridization. The API STAPH-IDENT strip utilizes a battery of 10 miniaturized biochemical tests, including alkaline phosphatase, urease, beta-glucosidase, beta-glucuronidase, and beta-galactosidase activity, aerobic acid formation from D-(+)-mannose, D-mannitol, D-(+)-trehalose, and salicin, and utilization of arginine. Reactions of cultures were determined after 5 h of incubation at 35 degrees C. Results indicated a high degree of congruence (greater than 90%) between the expedient API system and conventional methods for most species. The addition of a test for novobiocin susceptibility to the API system increased the accuracy of identification of S. saprophyticus, S. cohnii, and S. hominis, significantly. Several strains of S. hominis, S. haemolyticus, and S. warneri which were difficult to separate with the Kloos and Schleifer simplified scheme were accurately resolved by the API system.
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PMID:Identification of Staphylococcus species with the API STAPH-IDENT system. 675 90

A highly sensitive radiochemical assay used to measure the synthesis and regulation of the product of the argH gene, argininosuccinase, in an Escherichia coli system in vitro is described. With L-[guanidino-14C]argininosuccinic acid as a substrate, and in the presence of excess arginase and urease, 14CO2 is collected in a simply designed micro-vessel. With this method less than 1 nmol of product can be measured in the presence of various concentrations of L-arginine.
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PMID:The determination by radiochemical assay of argininosuccinase produced in an Escherichia coli system in vitro. 676 7

The properties of 279 Ps. aeruginosa strains were studied in 70 tests. The use of a synthetic peptone-free mineral medium for the determination of sugar oxidation was shown to have advantages over the use of liquid Giess' media. Ps. aeruginosa cultures isolated from human patients, animals, soil and water were characterized by a number of common signs, irrespective of their origin. The strains isolated from human patients were resistant practically to all antibiotics widely used in clinical practice; the cultures isolated from soil and water retained their sensitivity to antibiotics; the strains isolated from animals retained sensitivity to some antibiotics. To identify Ps. aeruginosa in practical bacteriological laboratories, the following parameters should be determined: mobility; the character of growth in Levine's and Ploskirev's media; ability to grow at 42 degrees C and 4 degrees C; the fermentation of carbohydrates in Olkenitsky's medium and their oxidation in a mineral medium; indole and hydroxide sulfide production; the methyl red and Voges--Proskauer reaction; the presence of pigments, oxidase, catalase, gelatinase, nitrate reductase and arginine dehydrolase, urease; resistance to antibiotics.
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PMID:[Morphologic, cultural, and biochemical properties of cultures of Pseudomonas aeruginosa isolated from patients, animals, and the environment]. 679 19

Hyperammonemia of varying magnitude was produced in young, male ferrets by either feeding them a purified diet containing low amounts of arginine or by intraperitoneal injections of jackbean urease. The responses were different depending on the method used to produce hyperammonemia. When hyperammonemia was produced by feeding a synthetic diet containing less than 0.2% arginine, ferrets developed encephalopathy soon after eating the diet and recovered after 4 hours. Although intraperitoneal injection of jackbean urease (100 IU/kg) caused severe hyperammonemia, ferrets did not become sick. Ferrets injected with 450 IU/kg of jackbean urease developed hyperammonemia but developed encephalopathy only after 15 hours. Ferrets showed remarkable capacity to tolerate elevated blood ammonia levels.
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PMID:Arginine requirement and ammonia toxicity in ferrets. 687 98

L-Canavanine competes with L-arginine for incorporation into vitellogenin secreted in vitro by the fat body of the female locust Locusta migratoria migratorioides. Incorporation of L-[guanidinooxy-14C]canavanine into vitellogenin has been established unequivocally by combined arginase and urease hydrolyses of the acid hydrolysate of antibody-precipitated canavanyl vitellogenin. Continued exposure of the fat body to canavanine decreases in vitro protein secretion but the proportion of canavanyl vitellogenin to native vitellogenin increases. Canavanine-mediated inhibition of fat body protein secretion is dependent on both the canavanine concentration and the arginine retention by the fat body. Canavanine replaces about 10% of the arginyl residues of canavanyl vitellogenin. The electrophoretic mobility of canavanyl vitellogenin is greater than that of native vitellogenin but the ability of this aberrant protein to react with vitellogenin antibody is unimpaired.
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PMID:In vitro incorporation of L-canavanine into vitellogenin of the fat body of the migratory locust Locusta migratoria migratorioides. 694 85

Three strains of Succinivibrio dextrinosolvens isolated from the rumen of cattle or sheep under diverse conditions grew well in a minimal medium containing glucose, minerals, cysteine, methionine, leucine, serine, ammonia, 1,4-naphthoquinone, p-aminobenzoic acid, and bicarbonate-carbonic acid buffer, pH 6.7. When menadione or vitamin K5 was substituted for 1,4-naphthoquinone, the growth rate was somewhat depressed. Growth was poor with vitamin K1 and ammonia, further addition of the amino acids aspartic acid, arginine, histidine, and tryptophan was necessary for good growth of type strain 24, but the other two strains grew well only in media containing ammonia. Strains C18 and 22B produced urease and grew well when ammonia replaced urea. When urea replaced ammonia, strain 24 grew poorly and urease activity could not be detected. Strain 24 required no B-vitamins, but the other two strains were stimulated by p-aminobenzoic acid. The methionine requirement was not placed by vitamin B12, betaine, or homocysteine. Cysteine was replaced by sulfide in strain 24 but less well in the other two strains. Very poor growth was obtained when sulfate replaced cysteine. The half-saturation constant for ammonia during growth of S. dextrinosolvens is more than 500 microM, a much higher value than that of many rumen bacteria.
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PMID:1,4-Naphthoquinone and other nutrient requirements of Succinivibrio dextrinosolvens. 712 52

The nitrogen excretory metabolism of the myxomycete Physarum polycephalum was studied. When cultured in partially defined broth medium or on agar, the principal excretory product was ammonia nitrogen. A small, variable quantity of urea was excreted in liquid culture. No uric acid or other purines were detected in the cultures. When microplasmodia were incubated with sodium [14C]bicarbonate, radioisotope was incorporated into citrulline, arginine, and urea. Incubation with L-[carbamoyl-14C]citrulline yielded labelled arginine, urea, and CO2. Substantial urease activity was found in extracts of the microplasmodia. These results, in conjunction with the lack of an absolute nutritional requirement for arginine, provide evidence that Physarum has a functional arginine biosynthetic pathway, an arginase, and a urease.
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PMID:Arginine synthesis and nitrogen excretion in the myxomycete Physarum polycephalum. 737 43

Wild-type Escherichia coli glutaminyl-tRNA synthetase (GlnRS; EC 6.1.1.18) poorly aminoacylates opal suppressors (GLN) derived from tRNA(Gln). Mutations in glnS (the gene encoding GlnRS) that compensate for impaired aminoacylation were isolated by genetic selection. Two glnS mutants were obtained by using opal suppressors differing in the nucleotides composing the base pair at 3.70: glnS113 with an Asp-235-->Asn change selected with GLNA3U70 (GLN carrying G3-->A and C70-->U changes), and glnS114 with a Gln-318-->Arg change selected with GLNU70 (GLN carrying a C70-->U change). The Asp-235-->Asn change was identified previously by genetic selection. Additional mutants were isolated by site-directed mutagenesis followed by genetic selection; the mutant enzymes have single amino acid changes (Lys-317-->Arg and Gln-318-->Lys). A number of mutants with no phenotype also were obtained randomly. In vitro aminoacylation of a tRNA(Gln) transcript by GlnRS enzymes with Lys-317-->Arg, Gln-318-->Lys, or Gln-318-->Arg changes shows that the enzyme's kinetic parameters are not greatly affected by the mutations. However, aminoacylation of a tRNA(Gln) transcript with an opal (UCA) anticodon shows that the specificity constants (kcat/Km) for the mutant enzymes were 5-10 times above that of the wild-type GlnRS. Interactions between Lys-317 and Gln-318 with the inside of the L-shaped tRNA and with the side chain of Gln-234 provide a connection between the acceptor end-binding and anticodon-binding domains of GlnRS. The GlnRS mutants isolated suggest that perturbation of the interactions with the inside of the tRNA L shape results in relaxed anticodon recognition.
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PMID:Functional communication in the recognition of tRNA by Escherichia coli glutaminyl-tRNA synthetase. 750 18

Mycobacterium tuberculosis urease (urea amidohydrolase [EC 3.5.1.5]) was purified and shown to contain three subunits: two small subunits, each approximately 11,000 Da, and a large subunit of 62,000 Da. The N-terminal sequences of the three subunits were homologous to those of the A, B, and C subunits, respectively, of other bacterial ureases. M. tuberculosis urease was specific for urea, with a Km of 0.3 mM, and did not hydrolyze thiourea, hydroxyurea, arginine, or asparagine. The enzyme was active over a broad pH range (optimal activity at pH 7.2) and was remarkably stable against heating to 60 degrees C and resistant to denaturation with urea. The enzyme was not inhibited by 1 mM EDTA but was inhibited by N-ethylmaleimide, hydroxyurea, acetohydroxamate, and phenylphosphorodiamidate. Urease activity was readily detectable in M. tuberculosis growing in nitrogen-rich broth, but expression increased 10-fold upon nitrogen deprivation, which is consistent with a role for the enzyme in nitrogen acquisition by the bacterium. The gene cluster encoding urease was shown to have organizational similarities to urease gene clusters of other bacteria. The nucleotide sequence of the M. tuberculosis urease gene cluster revealed open reading frames corresponding to the urease A, B, and C subunits, as well as to the urease accessory molecules F and G.
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PMID:Purification, characterization, and genetic analysis of Mycobacterium tuberculosis urease, a potentially critical determinant of host-pathogen interaction. 755 54


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