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)

Large amounts (250 liters) of dialysate fluid are needed for dialysis of patients with chronic kidney diseases. A reduction of these amounts is obtainable by regeneration. With the Redy system, in which urea is decomposed by the enzyme urease, only 5.5 liters of dialysate is used. Other systems depending solely on sorption of urea still need excessive amounts of sorbents and no alternative, in the form of stable chemical binding, is available. If, therefore, further reduction of dialysate volume is desired, the problem of urea removal must be solved.
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PMID:Regeneration of dialysate. 53 5

A new method for urea removal using a gas membrane is introduced along with some preliminary results. The membrane used was expanded polytetrafluoroethylene (E-PTFE) which is highly permeable to gaseous substances, while at the same time it is highly resistant to water permeation. In in vitro experiments using 10 mmol/L ammonia solution it was revealed that the single-pass reduction rate was approximately 95% at 30 degrees C at a flow rate of 200 ml/min. In animal experiments using four dogs, the extraction rate of urea was 40.4 +/- 4.4% after four hours of dialysis using 5 L dialysate. However, elevation of blood ammonia was observed in all dogs tested. Removal of ammonia by means of a gas membrane is considered to be feasible and has the possibility of being used for maintenance hemodialysis in combination with urease and charcoal.
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PMID:A new method of urea removal using urease and expanded polytetrafluoroethylene membrane. 53 26

The effect of some heavy metals on the urease activity was studied in a pure system using jack bean urease (JBU). While Mn showed no effect, copper reduced the enzyme activity more than did Zn or Fe at high concentrations (100 ppm). At a low concentration, iron reduced the enzyme activity more than at a high concentration. Inhibition of the urease activity was induced by less than 0.1 ppm Fe, 0.5 ppm Cu, and 10.0 ppm Zn. In the soil, these heavy metals inhibited the JBU in this order: Fe++ greater than Cu++ greater than Zn++. The possibility is discussed of using heavy metals to delay urea hydrolysis in soils.
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PMID:Studies on urea hydrolysis. Part 2. Effects of some heavy metals on urease activity. 55 Aug 59

The pathological effects of ureaplasmas on oviductal epithelium (ciliostasis and deciliation) were duplicated by adding ammonia to the medium as ammonium sulfate or by adding jack bean urease, which hydrolyzed the urea in the medium.
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PMID:Ureaplasmal epithelial lesions related to ammonia. 55 68

Urease activity was found in caecal contents (about 10 mg urea metabolised/g h) and crop contents (about 0-5 mg urea metabolised/g h):there was very low activity in the contents of the colon but none in the rest of the digestive tract. 2. The urease activity of the crop contents was not bacterial in origin but the soyabean meal contained in the diet was found to have comparable activity. 3. Diets low in non-essential nitrogen and based on soyabean, fish meal or fish meal plus 0-2% jack bean urease, did not support higher growth rates when supplemented with urea. 4. The livers of chicks fed on the diet containing fish meal, urea and urease had significantly higher concentrations of free non-essential amino acids than those of chicks fed on the same diet but with urease excluded This suggested that dietary urease affects the availability of ammonia for the synthesis of non-essential amino acids but not for growth.
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PMID:Urease activity in the digestive tract of the chick and its role in the utilisation of urea as a source of non-amino nitrogen. 56 Aug 98

Using the general concept of a dry multilayer analytical element, we can change chemical procedures and configurations to assay several blood components. In the assay of serum urea nitrogen, urease in the reagent layer catalyzes the hydrolysis of urea. A semipermeable membrane excludes aqueous base, but allows ammonia to diffuse to an underlying indicator layer. For the amylase determination, the enzyme hydrolyzes a dyed-starch substrate coated on top of the spreading layer; this produces small fragments, which diffuse to a registration layer. The increase of absorbance at 540 nm is correlated with amylase activity. Bilirubin complexes with a cationic polymer at the interface between the spreading and reagent layers. The direct reading at 460 nm allows determination of total bilirubin in the range 1 to 500 mg/liter. Tirglycerides are hydrolyzed in the spreading layer, and the resulting soluble glycerol readily diffuses into the reagent layer, where it is phosphorylated and subsequently oxidized by glycerophosphate oxidase to yield dihydroxyacetone phosphate and hydrogen peroxide. Peroxidase catalyzes production of a color commensurate with the hydrogen peroxide produced.
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PMID:Multilayer film elements for clinical analysis: applications to representative chemical determinations. 56 6

Urea has been shown to be an obligate intermediate in and the penultimate product of the catabolism of pyrimidine-ring nitrogen in Rhodosporidium toruloides (Rhodotorula). One of a series of mutants selected for its inability to utilize uracil as a sole source of nitrogen was unable to utilize urea also. The mutant accumulated urea and failed to form 14CO2 during supplementation with [2-14C]uracil. Radioautograms from the resulting cell extracts and media failed to reveal expected intermediates. Cell-free extracts of the mutant were shown to lack urease activity. Revertants of the mutant were essentially wild type in all tested attributes. Elements of the reductive pathway for pyrimidine catabolism are present in Rhodosporidium (O. A. Milstein and M. L. Bekker, J. Bacteriol. 127: 1-6, 1976), but is has not been determined whether this pathway is involved with production of urea.
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PMID:Urea: obligate intermediate of pyrimidine-ring catabolism in Rhodosporidium toruloides. 57 31

A flow-through system for the measurement of urea concentrations is described, using soluble urease and consecutive determination of liberated ammonium ions by a selective disc-electrode. The active component of the electrode membrane was the carrier-antibiotic nonactin which was incorporated in a polyvinylchloride matrix.
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PMID:[A NH(+4)-selective-enzymatic flow-through system. A method for the continuous enzymatic, electrochemical determination of urea, II (author's transl)]. 58 Oct 85

The present publication is the first of a series on the enzymatic urea tranformation in soil. With about 2,000 pure cultures of micro-organisms it was possible to prove the very good urea utilization by the soil micro-organisms (bacteria, actinomycetes, and fungi). Above all the fungi showed an excellent utilization of urea, while bacteria and actinomycetes were somewhat poorer. Contrary to this is the urease activity of these organisms, and that is the reason why fungi in soil may be regarded as short-time accumulators for urea nitrogen and must not be suppressed by inhibitors.
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PMID:[Contribution to the problem of microbially induced urea transformation in soil. I. On the ability of urea utilization by soil micro-organisms (author's transl)]. 60 75

An automated continuous flow method is described for the assay of plasmatic urea after hydrolysis by urease followed by NH+4 assay with glutamic-deshydrogenase. Precision and accuracy, comparison with chimical diacetyl-monoxim method are studied. The interaction of endogenous NH+4, the cost of the method are calculated.
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PMID:[Analysis of plasma urea by continuous flow method using enzymes]. 61 8


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