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)

Mutants of Apergillus nidulans with lesions in a gene, areA (formerly called amdT), have been isolated by a variety of different selection methods. The areA mutants show a range of pleiotropic growth responses to a number of compounds as sole nitrogen sources, but are normal in utilization of carbon sources. The levels of two amidase enzymes as well as urease have been investigated in the mutants and have been shown to be affected by this gene. Most of the areA mutants have much lower amidase-specific activities when grown in ammonium-containing medium, compared with mycelium incubated in medium lacking a nitrogen source. Some of the areA mutants do not show derepression of urease upon relief of ammonium repression. The dominance relationships of areA alleles have been investigated in heterozygous diploids, and these studies lend support to the proposal that areA codes for a positively acting regulatory product. One of the new areA alleles is partially dominant to areA+ and areA102. This may be a result of negative complementation or indicate that areA has an additional negative regulatory function. Investigation of various amdR; areA double mutants has led to the conclusion that amdR and areA participate in independent regulatory circuits in the control of acetamide utilization. Studies on an amdRc; areA double mutant indicate that areA is involved in derepression of acetamidase upon relief of ammonium repression.
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PMID:Studies on the role of the areA gene in the regulation of nitrogen catabolism in Aspergillus nidulans. 5 52

The growth and utilization of nitrogen by intensive Chlorella vulgaris in wastes from production of urea, containing 1300 mg NH4+-N and 4000 mg urea-N/1, was investigated. In these conditions only Chlorella vulgaris AA strain, adapted to high concentrations of ammonia nitrogen, was able to grow. The elimination of nitrogen by continuous cultures was 750 mg urea-N/1 with 5-day flow rate. A considerable part of the urea was hydrolized by urease bacteria and removed in the form of NH3. The effect of intermittent light on the growth of algae was also studied. The better growth than in continuous light, was obtained with alternate one hour periods of light and darkness. Good results were also obtained with the use of 12 hour light and 12 hour darkness.
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PMID:Studies on the purification of wastes from the nitrogen fertilizer industry by intensive algal cultures. IV. growth of Chlorella vulgaris in wastes with high nitrogen content in continuous and intermittent light. 6 57

A total of 834 bacterial strains isolated from urine were subjected to rapid biochemical and serological identification and rapid antimicrobial sensitivity testing using Autobac 1. For enterobacteria (742 strains) six tests (acetoin-, beta-galactosidase-, hydrogensulphide-, indole-, ornithin-decarboxylase-and urease-production) correctly identified to genus or species level more than 99% of the strains within four hours. Staphylococci and streptococci (92 strains) were identified with full accuracy within two hours using a rapid deoxyribonuclease assay and immunoelectroosmophoresis and coagglutination. The overall accuracy for the automated antibiotic susceptibility testing using Autobac was 93% as compared to the standard plate diffusion method. In terms of rapidity for 91% of the bacterial strains the susceptibility testing was completed within four hours. After five hours 99% of the strains were analysed. Our data indicate that rapid and automated assays can be accurate and furnish the physician with adequate data within 24 hours after receipt of a urinary specimen.
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PMID:Rapid identification and antibiotic sensitivity testing of bacteria isolated from clinical infections. 6 55

Forty-three strains of E. aerogenes isolated chiefly in Morocco and France have been studied. Thirty-five strains (81%) are surrounded with a thin capsule, antigenically related to Klebsiella capsular antigens: K4 (2 strains), K4, 59 (1 strain), K11 (2 strains), K26 (7 strains), K42 (5 strains), K59 (3 strains), K68 (14 strains). One strain is capsulated but not typable with Klebsiella capsular antisera. E. aerogenes and Klebsiella capsular antigens are not identical but share common fractions yielding cross reactions. To differenciate E. aerogenes from K. pneumoniae in addition with the three major characters, i.e. motility, ornithine-decarboxylase and urease, the author points out the value of growth in metahydroxybenzoate as sole source of carbon and energy (positive test with E. aerogenes and negative with K. pneumoniae).
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PMID:[Detection among "E. aerogenes" strains of capsular antigens related to those of "klebsiella". Interest of growth in metahydroxybenzoate to differenciate "E. aerogenes" and "K. pneumoniae" (author's transl)]. 7 14

The catabolic products of arginine metabolism were observed in Aphanocapsa 6308, a unicellular cyanobacterium, by thin layer chromatography of growth media, by limiting growth conditions, and by enzymatic analysis. Of the organic, nitrogenous compounds examined, only arginine supported growth in CO2-free media. The excretion of ornithine at a concentration level greater than citrulline suggested the existence in Aphanocapsa 6308 of the arginine dihydrolase pathway which produced ornithine, CO2,NH4,+ adenosine 5'-triphosphate. Its existence was confirmed by enzymatic analysis. Although cells could not grow on urea as a sole carbon source a very active urease and subsequently an arginase were also demonstrated, indicating that Aphanocapsa can metabolize arginine via the arginase pathway. The level of enzymes for both pathways indicates a lack of genetic control. It is suggested that the arginase pathway provides only nitrogen for the cells wheras the arginine dihydrolase pathway provides not only nitrogen, but also CO2 and adenosine 5'-triphosphate.
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PMID:Arginine catabolism in Aphanocapsa 6308. 10 70

Strains of purple sulfur bacteria (Chromatium minutissimum, Ectothiorhodospira shaposhnikovii, Thiocapsa roseopersicina, Lamprobacter modestohalophilus) and nonsulfur bacteria (Rhodopseudomonas palustris, Rh. spheroides, Rhodospirillum rubrum) grow in media containing urea as a source of nitrogen at concentrations from 0.5 to 5.0%. They can also utilize the carbon of urea and thus grow in the absence of bicarbonate. Urea is decomposed by all the studied purple bacteria with the participation of urease. In a number of strains, the enzyme is inducible and is synthesized only in the presence of urea. However, it is constitutive in certain purple bacteria (L. modestohalophilus, Rh. palustris, Rh. spheroides). The strains of purple bacteria differ in the activity of urease and in its susceptibility to ammonium ions.
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PMID:[Use of urea by purple bacteria]. 11 59

The urease and the beta-glucosidase for the identification of the mycobacteria were evaluated using 1,019 strains received for reference purposes in this laboratory in 1978. We found that the urease test was useful in the differential identification of BCG which, contrary to Mycobacterium bovis, gave a strong positive reaction in 3 h. The test was also useful to discriminate M. scrofulaceum from pigmented strains of M. avium. The beta-glucosidase test discriminated between M. tuberculosis and M. bovis and was useful to distinguish the niacine-positive strains of M. africanum which were usually negative in this test. The beta-glucosidase test was particularly useful in the differential identification of M. fortuitum and M. chelonei. In this report, the frequency distribution of the species which were submitted to this laboratory in 1978 was also shown and the results obtained for each of the conventional test procedures was presented.
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PMID:[Evaluation of urease and beta-glucosidase activity for the practical identification of mycobacteria (author's transl)]. 11 59

The 24 strains of Mycobacterium simiae described in this report were isolated from 12 black Africans, 6 from white Europeans, 5 from primates and 1 from a leprosy infected Armadillo. These strains form 3 groups having the similar morphologic and cultural properties as M. intracellulare. Two groups were similar with respect to pigmentation, urease activity and niacin production but differed serologically, the second group being of M. intracellulare serotype 18. The third group was less homogenous and was intermediate to M. simiae and M. intracellulare. Thus M. simiae belong to the M. avium-intracellulare-simiae-scrofulaceum (MAISS) complex. Two cases of well characterized pulmonary disease progressed like M. avium mycobacteriosis.
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PMID:[Relationships between "Mycobacterium simiae" and the "M. avium-intracellulare-scrofulaceum" complex (author's transl)]. 12 Jan 21

The regulation of the synthesis of the enzyme urease (urea amido hydrolase E.C. 3.5.1.5.) in Neurospora crassa was investigated. The biosynthesis of urease is repressed by ammonium ions. Under ammonium excess conditions the specific activity of urease decreases from 0.980 to 0.180 mumoles NH3/min/mg protein. By addition of cycloheximide it was shown that ammonia influences the synthesis of this enzyme. Enzyme induction by the substrate could be excluded. Even under the conditions of highest repression a specific activity of urease of 0.180 mumoles NH3/min/mg protein was measured. Possible causes of this constitutive enzyme level are discussed.
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PMID:[Repression of urease biosynthesis in Neurospora crassa by ammonium ions]. 12 30

The final products of the arginine catabolism that can be utilized as a nitrogen source in Neurospora crassa are ammonium, glutamic acid, and glutamine. The effect of these compounds on arginase induction by arginine was studied. In wild-type strain 74-A, induction by arginine was almost completely repressed by glutamic acid plus ammonium, whereas ammonium or glutamic acid alone had only moderate effects. Arginine products of catabolism also repressed arginase induction. A mutant, ure-1, which lacks urease activity, hyperinduced its arginase with arginine as a nitrogen source. The addition of either ammonium or glutamine produced effects similar to those in the wild-type strain. The effect of ammonium on arginase induction is mediated through its conversion into glutamine. This was demonstrated in mutant am-1, which lacks L-glutamate dehydrogenase activity. In this mutant, the effect of glutamic acid was reduced, and, with ammonium, it was completely lost. The addition of glutamine or glutamic acid plus ammonium to this strain decreased by threefold the induction of arginase by arginine. Proline, a final product of arginine catabolism, competitively inhibited arginase activity. This effect and the repression of arginase by glutamine are examples of negative modulation of the first enzyme in a catabolic pathway by its final products.
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PMID:Nitrogen regulation of arginase in Neurospora crassa. 14 62


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