Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As revealed the velocities of urea decomposition in the citrate donor plasma with soluble urease and urease immobilized by addition to carboxymethyl ester of cellulose, 2-(3'-amino-4'-methoxyphenyl)-sulphonylethyl ester of cellulose, diethylaminoester of cellulose, stained with dichlortriazine stain, or graft copolymere of cellulose and polyglycidylmetacrylate were sufficiently close to one another. Preparations of immobilized urease can be repeatedly used for urea decomposition in the citrate donor blood. Periodical treatment of the mentioned preparations with cystein solution led to a lesser decrease of enzymatic activity of the immobilized urease after repeated use.
 ...
PMID:[Possiblity of using immobilized urease for degradation of urea in blood plasma]. 87 Jan 9

1. Active ingredients retarding the carbon-transformation of straw (TCP, Thiuram, TBTO) also retard the nitrification. Their active period depends on the concentration and on the presence of organic matter. High doses of urea can inhibit the nitrification as well. 2. The activity of urease and the ammonification could not be influenced by adequate doses of the tested active ingredients. 3. The species of bacterium Azotobacter fixing the nitrogen from the air were inhibited by TCP, urea and D-chloramphenicol and promoted by Thiuram and WTZ II 277 after a short period of inhibition. 4. The fungi are very important in the biological nitrogen fixation after manuring straw and in prevention of nitrogen leaching in the autumn. 5. The sufficient concentration of the active ingredients to inhibit the nitrification are lower than the fungicidal concentrations. The soil bacteria could even not be restrained by doses of 5000 ppm. The bacilli were more retarded in presence of organic matters than in a not manured soil.
 ...
PMID:[The effect of biocides on the microflora of soils and their degradation. 4. The influence of substances inhibiting the straw decomposition on the nitrogen transformation (author's transl)]. 87 9

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.
 ...
PMID:Rumen bacterial urease requirement for nickel. 88 74

1. p-Nitrophenyl carbamate and thiourea have been shown to be substrates for urease (urea amidohydrolase, EC 3.5.1.5) 2. Urease has been shown to have a lower Km, 0.67 mM, with p-nitrophenyl carbamate than with urea, 2.0 mM. 3. The V of urease for the hydrolysis of urea, p-nitrophenyl carbamate and thiourea has been shown to be the same, indicating a common rate-limiting step. 4. A mechanism has been proposed for urease where the initial rate-limiting step is the release of a molecule of ammonia from the substrates.
 ...
PMID:The interaction of p-nitrophenyl carbamate with urease. 88 23

The overall rate of reaction of a gel-immobilized urease particle necessarily depends upon the hydrogen ion concentrations within the particle. When the particle is unbuffered, the internal hydrogen ion concentrations are a consequence of the local rates of reaction and the rate of egress of the products of hydrolysis. A simple apparatus has been devised which allows a fairly rapid determination of the hydrogen ion concentration in the center of a particle for any given size, enzyme concentration, substrate concentration, and external pH. The products of urea hydrolysis are self-buffering in the region of pH 8.83 and for an external pH less than the self-buffering pH, the pH within the particle is increased because of the reaction. When the external pH is greater than the self-buffering pH, the converse occurs. The pH at the center of the particle approaches the self-buffering pH with an increase in particle size and enzyme concentration. The external increase in the external substrate concentration has a limited effect, simply rendering the local rates of reaction to be of zero order. The center-line pH and therefore all internal hydrogen ion concentrations depend upon the parameter L square root pe and the external pH. Differences between the external and center-line pH values of the order of units are unexceptional. The implications of the internal pH profiles on the local and overall rates of reaction are explored.
 ...
PMID:Characteristics of unbuffered gel-immobilized urease particles. I. Internal pH. 88 31

We used a differential thermal detector in conjunction with an immobilized urease reactor to determine urea in serum. Samples (120 mul) are introduced into a flow stream and passed through an "adiabatic" column, which is packed with enough insolubilized urease to completely convert urea to ammonia and carbon dioxide. Measured temperature changes are directly proportional to the serum urea concentration. Urea in the presence of protein, bilirubin, and hemoglobin can thus be rapidly, simply, and inexpensively measured. Results correlate well with those obtained by the manual diacetyl monoxime and urease/indophenol methods.
 ...
PMID:Rapid-flow enthalpimetric determination of urea in serum, with use of an immobilized urease reactor. 94 41

A differential agar medium for the identification of Ureaplasma urealyticum in primary cultures of clinical specimens is described. The differential medium (no. A7) is specific for the identification of U. urealyticum and other members of the genus Ureaplasma. Large-colony, classical Mycoplasma and Acholeplasma species and Proteus L colonies are unreactive on this differential medium. The medium incorporates the biochemical principle of the direct spot test for urease in colonies of Ureaplasma and contains added urea and a sensitive indicator of ammonia, manganous sulfate. Ureaplasma colonies on this medium are identified as dark golden-brown or rich deep-brown colonies, in sharp contrast to the light background of the medium, when viewed by direct transmitted illumination under the low power of the microscope.
 ...
PMID:Differential agar medium (A7) for identification of Ureaplasma urealyticum (human T mycoplasmas) in primary cultures of clinical material. 95 Mar 79

The kinetic determination of urea based on the urea/glutamate dehydrogenase method was adapted for the LKB Reaction Rate Analyzer System 8600. A ratio of sample to reagent volume of 1:50 ensures linearity up to 33.3 mmol/l with a day to day precision of 5%. Parallel studies with the urease/glutamate dehydrogenase method were performed with the CentrifiChem System and with the manual Berthelot/Salicylate method.
 ...
PMID:[Kinetic determination of urea with the LKB system (author's transl)]. 95 32

Measurements of urease activity of various cell fractions of U. urealyticum showed that this activity was confined to the soluble fraction of the cytoplasm. It was attempted to devise a method for electron microscopic detection of the sites of urease activity based on precipitation of electron dense MnO2 at the alkaline pH created by hydrolysis of urea. The results obtained by this method supported the previous results indicating a cytoplasmatic localization of the urease activity in the cells. Helical ribosome patterns were observed when glutaraldehyde fixed cells were treated with the cytochemical test solutions.
 ...
PMID:Localization of urease activity in Ureaplasma urealyticum cells. 96 32

Low values for urea were found in samples of ruminal fluid of sheep fed concentrate rations if urea determination was carried out by the urease method. The present paper describes a both simple and sensitive colorimetric method of analysis using diacetyldioxime. The method is suitable for determining urea in coloured solutions such as ruminal fluid or silage extracts.
 ...
PMID:[Determination of urea in the ruminal fluid of sheep]. 97 Nov 7


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>