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)

Lambs were fed a basal purified diet low in nickel (60 ppb) or the basal diet supplemented with 5 ppm of nickel to determine if rumen bacterial urease was a nickel-requiring enzyme. Two collection periods with lambs fed a diet in which all the nitrogen was supplied as preformed protein (casein) indicated that ruminal urease activity was much lower in lambs fed the low nickel diet. When 1% urea was added to the basal diet, urease activity increased slightly with both treatments; however, bacterial urease activity was still much higher in the lambs receiving 5 ppm of nickel. Ruminal volatile fatty acids were not influenced by dietary nickel. Ruminal urease requires nickel for maximal activity.
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PMID:Rumen bacterial urease requirement for nickel. 88 74

1. In a preliminary experiment, growth of conventional chicks given a basal diet containing adequate amounts of all the essential but none of the non-essential amino acids was improved by supplements of 10-3 g urea or 50-4 g glutamic acid/kg diet or both. 2. In the main study the effects of supplementing the basal diet with 20-6 g urea/kg were compared in groups of sixteen germ-free and conventional chicks. 3. The germ-free chicks did not benefit from the urea supplement whereas the conventional birds showed improved food conversion efficiency and significantly better growth. 4. In both environments nitrogen retention ((mg N intake-mg N excreted)divideg food intake) was higher in the birds given urea, but N utilization ((mg N intake-mg N excreted)dividemg N intake) was reduced. This reduction was greater in the germ-free birds. 5. There was a small increase in plasma ammonia concentration in the germ-free birds given urea but a significantly greater increase in the corresponding conventional group. 6. Plasma uric acid concentrations were variable in both groups, and much lower than the normal range. They followed a similar pattern to the plasma ammonia values. 7. More insoluble N was excreted by the conventional chicks given urea than by the corresponding germ-free group, or by either group given the basal diet. 8. It was concluded that the gut micro-organisms are responsible for the growth-promoting effect of urea, presumably through release of ammonia by bacterial ureas (EC 3.5.1.5) and its consequent incorporation into amino acids.
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PMID:The role of the gut microflora in the utilization of dietary urea by the chick. 95 38

Nitrogen-free analogues of essential amino acids, when administered with those essential amino acids for which analogues are ineffective or unavailable, exert three actions that may be beneficial in protein-deficient or protein-intolerant subjects. First, they bring about an increase in the concentrations of essential amino acids in the blood at the expense of the concentrations of certain non-essential amino acids, notably alanine and glutamine. This effect is most readily demonstrated in children with congenital defects of the urea cycle enzymes, but can also be seen during daily therapy of adults with portal-systemic encephalopathy. Second, these compounds promote nitrogen balance through their suppressive effect on urea synthesis (an effect not attributable to re-utilization of ammonia derived from urease action in the gut). This action is demonstrable in obese subjects who are already conserving nitrogen maximally at the end of a prolonged fast and can also be shown in the first week of fasting when the branched-chain keto acids alone are administered. In both situations, improved nitrogen conservation persists long after the analogues are metabolized, suggesting enzyme adaptations. In chronic uremics, nitrogen balance can be maintained in some (but not all) patients on very low nitrogen intakes. Third, these mixtures may delay or reverse the progressive decline in glomerular filtration rate characteristic of chronic renal failure in some cases: thus, for example, 5 of 6 patients taken off chronic dialysis have maintained lower serum urea concentrations without evidence of protein malnutrition for periods of 2-24 months.
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PMID:Evidence for an anabolic action of essential amino acid analogues in uremia and starvation. 107 39

Gyrocotyle fimbriata isolated from the spiral valve of Hydrolagus colliei were washed, then held in a filtered seawater-penicillin-Tris buffer medium. Ammonia and urea release to the medium declined together and ammonia production was minimal when the urea concentration was below detectable limits. Alanine and smaller amounts of glycine were released to the medium at a more constant rate. After 12 hr the alanine-glycine excretion was more than 20 times the ammonia excretion. L-arginine, L-serine, L-histidine, and urea were most effective in stimulating ammonia production by whole worms; other L-amino acids were essentially ineffective. L-glutamate dehydrogenase, L-amino acid oxidase, uricase, and ornithine transcarbamylase were below detectable levels. L-serine dehydrase, L-arginase, L-histidase, and urease were detected in tissue homogenates and probably account for most of the endogenous ammonia production. L-arginase has a molecular weight of 28,000 by Sehpadex gel filtration. The high levels of glutamate-pyruvate transaminase and lower levels of glutamate-oxalacetate transaminase correlate with the high level of alanine excretion. It is concluded that (1) ammonia production is not strongly linked to the overall energy metabolism of Gyrocotyle and is probably a result of a series of unrelated enzymatic reactions such as the action of urease of urea from the tissue of the rat fish, and (2) alanine and glycine are the major nitrogen excretory products and their production is linked to the energy metabolism of Gyrocotyle.
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PMID:Ammonia formation and amino acid excretion by Gyrocotyle fimbriata (Cestoidea). 111 78

Studies were conducted on the effect of four different hydroxamic acids (HA), hydroxyurea, acetohydroxamic acid, p-flurobenzoylhydroxamic acid and sorbylhydroxamic acid, on the growth and urease activity of Corynebacterium renale. The addition of each of these HA, at concentrations ranging form 10(-3) to 10(-5) M, to medium containing urea as the sole nitrogen source resulted in a lengthened lag period of growth the extent of which depended upon the concentration of each HA tested as well as the structure of the compound; that is, the size and (or) complexity of the side chain attached to the common terminal group of the molecule. However, the maximal growth levels achieved following conclusion of the exponential phase were not affected by the HA. Investigations on the effect of these HA on the urease activity of intact cells as well as cell-free extracts revealed that in each case the enzymatic activity was inhibited by each of the HA tested. The extent of inhibition with the intact cells was aobut one-half of that observed with cell-free extracts. Direct incubation of cell-free extracts as well as intact cells with each of the HA tested was required for maximal inhibition.
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PMID:Effect of hydroxamic acids on growth and urease activity in Corynebacterium renale. 126 May 45

Three laboratory-prepared urease reagents were compared with a commercial preparation supplied for routine use on the Beckman Blood Urea Nitrogen Analyzer. There were discrepancies in results for urea nitrogen among the four urease reagents when matching serum and the corresponding oxalate/fluoride treated plasma were compared as measured with the Beckman Analyzer and continuous-flow (AutoAnalyzer) method. All four urease preparations were affected by fluoride, but to different extents. We believe that an effective laboratory reagent can be prepared in the laboratory at significantly lower cost.
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PMID:Four commercial urease reagents and a laboratory-prepared reagent compared for analysis of blood urea nitrogen with the Beckman analyzer. 126 Oct 19

Helicobacter pylori produces a potent urease that is believed to play a role in the pathogenesis of gastroduodenal diseases. Four genes (ureA, ureB, ureC, and ureD) were previously shown to be able to achieve a urease-positive phenotype when introduced into Campylobacter jejuni, whereas Escherichia coli cells harboring these genes did not express urease activity (A. Labigne, V. Cussac, and P. Courcoux, J. Bacteriol. 173:1920-1931, 1991). Results that demonstrate that H. pylori urease genes could be expressed in E. coli are presented in this article. This expression was found to be dependent on the presence of accessory urease genes hitherto undescribed. Subcloning of the recombinant cosmid pILL585, followed by restriction analyses, resulted in the cloning of an 11.2-kb fragment (pILL753) which allowed the detection of urease activity (0.83 +/- 0.39 mumol of urea hydrolyzed per min/mg of protein) in E. coli cells grown under nitrogen-limiting conditions. Transposon mutagenesis of pILL753 with mini-Tn3-Km permitted the identification of a 3.3-kb DNA region that, in addition to the 4.2-kb region previously identified, was essential for urease activity in E. coli. Sequencing of the 3.3-kb DNA fragment revealed the presence of five open reading frames encoding polypeptides with predicted molecular weights of 20,701 (UreE), 28,530 (UreF), 21,744 (UreG), 29,650 (UreH), and 19,819 (UreI). Of the nine urease genes identified, ureA, ureB, ureF, ureG, and ureH were shown to be required for urease expression in E. coli, as mutations in each of these genes led to negative phenotypes. The ureC, ureD, and ureI genes are not essential for urease expression in E. coli, although they belong to the urease gene cluster. The predicted UreE and UreG polypeptides exhibit some degree of similarity with the respective polypeptides encoded by the accessory genes of the Klebsiella aerogenes urease operon (33 and 92% similarity, respectively, taking into account conservative amino acid changes), whereas this homology was restricted to a domain of the UreF polypeptide (44% similarity for the last 73 amino acids of the K. aerogenes UreF polypeptide). With the exception of the two UreA and UreB structural polypeptides of the enzyme, no role can as yet be assigned to the nine proteins encoded by the H. pylori urease gene cluster.
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PMID:Expression of Helicobacter pylori urease genes in Escherichia coli grown under nitrogen-limiting conditions. 131 13

An urea-ENFET (Enzyme field effect transistor) probe was made by covering one of the grids of the dual ISFET (Ion sensitive field effect transistor) with a membrane of cross-linked bovine serum albumin (BSA)-urease and the other with cross-linked BSA, and the response characteristics of the probe was then tested through differential measurements. In different concentrations of phosphate buffer, the sensor responded to various concentrations of urea solution within 10-60s. From the calibration curve plotted on logarithmic scales a linear concentration range of 1.0-8.0 mg/dl was acquired, and the correlation coefficient and response sensitivity were 0.997 and 50mV/dec. (mg/dl), respectively. However, in dilute urea solution, the sensor responded linearly to the contents of urea over the range of concentration of 0.1-1.0 mg/dl with a correlation coefficient of 0.998 and a response sensitivity of 12-15mV/mg/dl. The standard deviation and the variation coefficient for 20 performances responding to 100mg/dl urea in 0.01M pH7.0 phosphate buffer were found to be 1.39mV and 1.44%, respectively. The urea-ENFET was used for the determination of BUN (Blood urea nitrogen) and the BUN values were compared with those determined by enzymatic method, the repression equation and correlation coefficient for 50 assays were y = -0.1272 + 0.9695x and r = 0.9912, respectively. When the urea-ENFET was used for determining urea either in buffer solution or in serum for 250 runs over a period of 1.5 months (the enzyme FET was stored at 4 degrees C between measurements during this period), the observed decrease of response sensitivity was only about 10%.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Miniature urea sensor based on H(+)-ion sensitive field effect transistor and its application in clinical analysis. 133 30

To evaluate partial or total replacement of renal function using gut, we measured in vivo transport of nitrogen metabolites, electrolytes, and water into a jejunal segment configured as a continent reservoir in the dog. Reservoir contents were sampled and analyzed at serial time intervals during a 3-h period after instillation of solution containing (in mM) 40 NaCl, 10 NaHCO3, 220 mannitol, pH 8.5, without or with added urease. At 10 min postinstillation, the amount of urea in the solution without added urease was 3-5 times greater than in the presence of added urease, but accumulation of NH4+ was 14-21 times greater in the solution containing added urease, giving a luminal NH4+ concentration up to 10,000 times that of plasma. In the absence of urease, HCO3- concentration fell to 0, and pH declined to 6 at 3 h; in the presence of urease, HCO3- concentration was 4.5 mM, and pH was 7.8 at 3 h. We conclude 1) urea is secreted by the reservoir; 2) H+ is secreted and/or formed in the reservoir; 3) in the presence of urease, urea hydrolyzed to NH3 is converted to NH4+ by H+ and trapped in the lumen; and 4) in the urease solution, H+ binding by NH3 preserves luminal HCO3-, maintaining the initial pH. Thus the continent jejunal reservoir may supplement or replace impaired renal function.
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PMID:Transport properties of an in situ jejunal reservoir in dogs. 155 68

The NAC (nitrogen assimilation control) protein from Klebsiella aerogenes is a LysR-like regulator for transcription of several operons involved in nitrogen metabolism, and couples the transcription of these sigma 70-dependent operons to regulation by the sigma 54-dependent NTR system. NAC activates expression of operons (e.g. histidine utilization, hut), allowing use of poor nitrogen sources, and represses expression of operons (e.g. glutamate dehydrogenase, gdh) allowing assimilation of the preferred nitrogen source, ammonium. NAC is both necessary and sufficient to activate transcription, but the expression of the nac gene is totally dependent on the central nitrogen regulatory system (NTR) and RNA polymerase carrying the sigma 54 sigma factor (RNAP sigma 54). Nitrogen starvation signals the NTR system to transcribe nac, and NAC activates the transcription of hut, put (proline utilization), and urease. NAC does not affect the transcription of RNAP sigma 54-dependent operons like ginA or nifLA, which respond directly to the NTR system, but activates transcription of RNAP sigma 70-dependent operons. Thus NAC acts as a bridge between RNAP sigma 70-dependent operons like hut and the RNAP sigma 54-dependent NTR system. The activation of operons like hut by NAC in response to nitrogen starvation is at least superficially similar to their activation by CAP-cAMP in response to carbon and energy starvation.
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PMID:The role of the NAC protein in the nitrogen regulation of Klebsiella aerogenes. 166 20


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