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:3.5.1.5 (urease)
7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperammonemia is an important cause of cerebral dysfunction in liver failure. We used two well-established models to induce hyperammonemia in rats, injection of urease and injection of methionine sulfoximine (MSO). Urease gave a 10-fold increase in blood ammonia while MSO, a glutamine synthetase inhibitor, gave a 4-fold increase in blood ammonia with no increase in brain glutamine levels. We observed a 2-fold increase in 5-HT1A receptor (5-HT1A-R) expression ([3H] 8-OH-DPAT binding) in hippocampus, and little change elsewhere, including thalamus in both models, thus eliminating a role for increased glutamine in the receptor induction. In contrast, a 4 to 8-fold increase in 5-HT1A-R mRNA was observed both in hippocampus and thalamus, suggesting some post-transcriptional regulation. In the absence of glutamine, ammonium acetate treatment of a hippocampal cell line which had been engineered to stably express the 5-HT1A-R (HN2-5) gave a 1.5-fold increase in [3H] 8-OH-DPAT binding and a 4-fold increase in the mRNA levels for the 5-HT1A-R. We conclude that the cell line HN2-5 is a good model for studying some of the biochemical sequelae of hyperammonemia and that changes in brain function are not only at the metabolic level, as thought earlier, but can also occur at the transcriptional level.
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PMID:Hyperammonemia increases serotonin 1A receptor expression in both rat hippocampus and a transfected hippocampal cell line, HN2-5. 767 72

Proteus mirabilis urease catalyzes the hydrolysis of urea, initiating the formation of urinary stones. The enzyme is critical for kidney colonization and the development of acute pyelonephritis. Urease is induced by urea and is not controlled by the nitrogen regulatory system (ntr) or catabolite repression. Purified whole-cell RNA from induced and uninduced cultures of P. mirabilis and Escherichia coli harboring cloned urease sequences was probed with a 4.2-kb BglI fragment from within the urease operon. Autoradiographs of slot blots demonstrated 4.2- and 5.8-fold increases, respectively, in urease-specific RNA upon induction with urea. Structural and accessory genes necessary for urease activity, ureD, A, B, C, E, and F, were previously cloned and sequenced (B. D. Jones and H. L. T. Mobley, J. Bacteriol. 171:6414-6422, 1989). A 1.2-kb EcoRV-BamHI restriction fragment upstream of these sequences confers inducibility upon the operon in trans. Nucleotide sequencing of this fragment revealed a single open reading frame of 882 nucleotides, designated ureR, which is transcribed in the direction opposite that of the urease structural and accessory genes and encodes a 293-amino-acid polypeptide predicted to be 33,415 Da in size. Autoradiographs of sodium dodecyl sulfate-polyacrylamide gels of [35S]methionine-labeled polypeptides obtained by in vitro transcription-translation of the PCR fragments carrying only ureR yielded a single band with an apparent molecular size of 32 kDa. Fragments carrying an in-frame deletion within ureR synthesized a truncated product. The predicted UreR amino acid sequence contains a potential helix-turn-helix motif and an associated AraC family signature and is similar to that predicted for a number of DNA-binding proteins, including E. coli proteins that regulate acid phosphatase synthesis (AppY), porin synthesis (EnvY), and rhamnose utilization (RhaR). These data suggest that UreR governs the inducibility of P. mirabilis urease.
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PMID:Proteus mirabilis urease: transcriptional regulation by UreR. 767 44

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 most important phosphates involved in urinary stone disease are carbonate apatite, brushite, and struvite. Overall, phosphate stones account for 12-20% of all stones, with a downward trend for struvite and an increase in carbonate apatite being observed in the last decade. The physicochemical basis for the formation of phosphate calculi is supersaturation. Once the solubility product has been exceeded, a metastable process of supersaturation begins, with slow crystalline growth. If a critical limit of supersaturation is exceeded, large-scale spontaneous precipitation of crystals occurs in a second stage. No urinary tract infection is involved in brushite stone formation. Although infection is not a prerequisite for the formation of carbonate apatite stones, infective conditions favor carbonate apatite formation. Struvite is the characteristic infection calculus, formed as a result of urinary tract infection with urease-producing bacteria. During the first episode of urinary stone disease a definitive diagnosis of the type of stone involved is very difficult without analysis of the latter by infrared spectroscopy or X-ray diffraction. In recurrent disease, appropriate treatment can be initiated on the basis of the previous stone analysis in the majority of cases. The best means of preventing recurrent disease involving any type of phosphate stone is definitive calculus removal by shock-wave lithotripsy, percutaneous stone removal, or open surgery (especially in children). Chemolysis via acidification of the urine with Suby G solution or hemicidrin supported by oral acidification, achieved by the metabolism of L-methionine, and antibiotic therapy (especially for infectious stones) are important adjuvant modalities of therapy. After therapy of phosphate stones, metaphylaxis involving controlled urinary acidification with L-methionine supports the treatment of infection and, at a pH value of less than 6.2 and urine dilution to 2.5 l/24 h, prevents the crystallization of struvite, brushite, and carbonate apatite.
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PMID:Causes of phosphate stone formation and the importance of metaphylaxis by urinary acidification: a review. 1055 50

Homocystinuria types I, II and III are characterized by different etiologies, biochemical abnormalities and therapeutic measures. For this reason, differential diagnosis is critical for effective treatment. We describe here a rapid and simple procedure for establishing a differential diagnosis of the three types of homocystinuria by analyzing the urine of patients. This procedure, which consists of urease treatment, stable isotope dilution and GC-MS, enables a simultaneous quantification of methionine, homocystine, cystine, methylmalonate, orotate, uracil and creatinine. Analysis with this procedure showed that a case of homocystinuria type I, who progressed into transient megaloblastic anemia, secondarily excreted an increased concentration of orotate, which normalized after treatment with folate and vitamin B12. Therefore, the present diagnostic procedure not only enables rapid differential diagnosis of homocystinuria, but also should prove useful for monitoring the disease state and understanding the nutritional condition and therapeutic state of patients, which in turn can be used to evaluate the efficacy of treatment.
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PMID:Differential diagnosis of homocystinuria by urease treatment, isotope dilution and gas chromatography-mass spectrometry. 1089 84

The urease from the picoplanktonic oceanic Prochlorococcus marinus sp. strain PCC 9511 was purified 900-fold to a specific activity of 94.6 micromol urea min(-1) (mg protein)(-1) by heat treatment and liquid chromatography methods. The enzyme, with a molecular mass of 168 kDa as determined by gel filtration, is the smallest urease known to date. Three different subunits with apparent molecular masses of 11 kDa (gamma or UreA; predicted molecular mass 11 kDa), 13 kDa (ss or UreB; predicted molecular mass 12 kDa) and 63 kDa (alpha or UreC; predicted molecular mass 62 kDa) were detected in the native enzyme, suggesting a quaternary structure of (alphassgamma)(2). The K:(m) of the purified enzyme was determined as being 0.23 mM urea. The urease activity was inhibited by HgCl(2), acetohydroxamic acid and EDTA but neither by boric acid nor by L-methionine-DL-sulfoximine. Degenerate primers were designed to amplify a conserved region of the ureC gene. The amplification product was then used as a probe to clone a 5.7 kbp fragment of the P. marinus sp. strain PCC 9511 genome. The nucleotide sequence of this DNA fragment revealed two divergently orientated gene clusters, ureDABC and ureEFG, encoding the urease subunits, UreA, UreB and UreC, and the urease accessory molecules UreD, UreE, UreF and UreG. A putative NtcA-binding site was found upstream from ureEFG, indicating that this gene cluster might be under nitrogen control.
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PMID:Prochlorococcus marinus strain PCC 9511, a picoplanktonic cyanobacterium, synthesizes the smallest urease. 1110 68

When the fungus Gibberella fujikuroi ATCC 12616 was grown in fermentor cultures, both intracellular kaurene biosynthetic activities and extracellular GA(3) accumulation reached high levels when exogenous nitrogen was depleted in the culture. Similar patterns were exhibited by several nonrelated enzymatic activities, such as formamidase and urease, suggesting that all are subject to nitrogen regulation. The behavior of the enzymes involved in nitrogen assimilation (glutamine synthetase, glutamate dehydrogenase, and glutamate synthase) during fungal growth in different nitrogen sources suggests that glutamine is the final product of nitrogen assimilation in G. fujikuroi. When ammonium or glutamine was added to hormone-producing cultures, extracellular GA(3) did not accumulate. However, when the conversion of ammonium into glutamine was inhibited by L-methionine-DL-sulfoximine, only glutamine maintained this effect. These results suggest that glutamine may well be the metabolite effector in nitrogen repression of GA(3) synthesis, as well as in other nonrelated enzymatic activities in G. fujikuroi.
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PMID:Glutamine Involvement in Nitrogen Control of Gibberellic Acid Production in Gibberella fujikuroi. 1634 28

Cultured soybean (Glycine max, Kanrich variety) cells grow with 25 mm urea as the sole nitrogen source but at a slower rate than with the Murashige and Skoog (MS) (Physiol. Plant. 15: 473-497, 1962) nitrogen source of 18.8 mm KNO(3) and 20.6 mm NH(4)NO(3). Growth with urea is restricted by 18.8 mm NO(3) (-), 50 mm methylammonia, 10 mm citrate or 100 mum hydroxyurea, substances which are much less restrictive or nonrestrictive in the presence of ammonia nitrogen source. The restrictive conditions of urea assimilation were examined as possible bases for selection schemes to recover urease-overproducing mutants. Since urease has higher methionine levels than the soybean seed proteins among which it is found, such selections may be a model for improving seed protein quality by plant cell culture techniques.Callus will not grow with 1 mm urea plus 18.8 mm KNO(3). Urease levels decrease 80% within two divisions after transfer from MS nitrogen source to 1 mm urea plus 18.8 mm KNO(3). Hydroxyurea is a potent inhibitor of soybean urease and this appears to be the basis for its inhibition of urea utilization by callus cells.Stationary phase suspension cultures grown with MS nitrogen source exhibit trace or zero urease levels. Soon after transfer to fresh medium (24 hours after escape from lag), urease levels increase in the presence of both MS or urea nitrogen source. However, the increase is 10 to 20 times greater in the presence of urea. NH(4)Cl (50 mm) lowers urease induction by 50% whereas 50 mm methylammonium chloride results in more drastic reductions in urea-stimulated urease levels. Citrate (10 mm) completely blocks urease synthesis in the presence of urea.Ammonia and methylammonia do not inhibit soybean urease nor do they appreciably inhibit urea uptake by suspension cultures. It appears likely that methylammonia inhibits urea utilization in cultured soybean cells primarily due to its "repressive" effect on urease synthesis.Citrate does not inhibit urease activity in vitro and exhibits only a partial inhibition (0-50% in several experiments) of urea uptake. It appears likely that the citrate elimination of urease production by cultured soybean cells is due to its chelation of trace Ni(2+) in the growth medium. Dixon et al. (J. Am. Chem. Soc. 97: 4131-4133, 1975) have reported that jack bean (Canavalia ensiformis) urease contains nickel at the active site.
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PMID:Nitrogen metabolism in soybean tissue culture: I. Assimilation of urea. 1665 77

Foliar urea application on barley plants increased leaf urease activity for 5 hours with a peak of 20-fold at 2 hours. To discern the mode of urease induction, urea with or without inhibitors and [(35)S]methionine were incubated with leaf sections for different lengths of time. Urease was extracted, partially purified, electrophoresed, and then quantified by fluorogram. Five urease (U) isozymes were separated by PAGE. U(a) and U(b) might be polymers or complexes that occurred only at the peak of induced activity. U(1) and U(2) appeared at 0.5 and 0.75 hour, respectively, after urea induction, peaked at 2 hours, and persisted only in treated leaves for several additional hours indicating that they are transient inducible forms. U(3) was the constitutive form present in control and treated leaves. Induction with cordycepin or cycloheximide completely prevented urea stimulated activity and nullified the existence of isozymes U(a), U(b), U(1), and U(2). (35)S-U(1), which was labeled in the last hour of induction, appeared on fluorogram 1 hour after induction, peaked at 2 hours, and declined at 3 hours. Results indicated that de novo synthesis of urease is activated by the influx of urea.
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PMID:Induction of barley leaf urease. 1666 13

Roots of young soybean (Glycine max [L.] Merr.) plants (up to 25 days old) contain two distinct urease isozymes, which are separable by hydroxyapatite chromatography. These two urease species (URE1 and URE2) differ in: (a) electrophoretic mobility in native gels, (b) pH dependence, and (c) recognition by a monoclonal antibody specific for the seed ("embryo-specific") urease. By these parameters root URE1 urease is similar to the abundant embryo-specific urease isozyme, while root URE2 resembles the "ubiquitous" urease which has previously been found in all soybean tissues examined (leaf, embryo, seed coat, and cultured cells). The embryo-specific and ubiquitous urease isozymes are products of the Eu1 and Eu4 structural genes, respectively. Roots of the eu1-sun/eu1-sun genotype, which lacks the embryo-specific urease (i.e. ;seed urease-null'), contain no URE1 urease activity. Roots of eu4/eu4, which lacks ubiquitous urease, lack the URE2 (leaflike) urease activity. From these genetic and biochemical criteria, then, we conclude that URE1 and URE2 are the embryo-specific and ubiquitous ureases, respectively. Adventitious roots generated from cuttings of any urease genotype lack URE1 activity. In seedling roots the seedlike (URE1) activity declines during development. Roots of 3-week-old plants contain 5% of the total URE1 activity of the radicle of 4-day-old seedlings, which, in turn, has approximately the same urease activity level as the dormant embryonic axis. The embryo-specific urease incorporates label from [(35)S]methionine during embryo development but not during germination, indicating that there is no de novo synthesis of the embryo-specific (URE1) urease in the germinating root. We conclude that the seedlike urease (URE1) found in roots of young soybean plants is a remnant of the Eu1-encoded, abundant, embryo-specific urease which accumulates in the embryonic root axis during seed development.
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PMID:Soybean Roots Retain the Seed Urease Isozyme Synthesized during Embryo Development. 1666 65


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