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)

We describe a new enzymic colorimetric method in which urea is measured in serum by use of a single reagent mixture. Ammonia produced by urea hydrolysis, catalyzed by urease, reacts with glutamate and ATP in the presence of glutamine synthetase. The ADP so produced is assayed in reactions catalyzed sequentially by pyruvate kinase and pyruvate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is measured at 500 or 550 nm in a reaction catalyzed by horseradish peroxidase, with phenol/4-aminophenazone as the chromogen. The reaction is complete in 15 min at 37 degrees C. The standard curve is linear up to a urea concentration of 40 mmol/L. Precision is good; CVs ranged from 2.5% to 3.1%. Results by the present method compared well with those by a candidate Reference Method and are not subject to interferences from commonly used drugs and anticoagulants.
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PMID:Enzymic urea assay: a new colorimetric method based on hydrogen peroxide measurement. 256 17

A rapid enzymatic assay method for ammonia was developed by using glutamine synthetase from glutamate-producing bacteria together with pyruvate kinase, lactate dehydrogenase, and NADH. The time required for determination of 25 nmol of ammonia was 5 min with 1 unit of glutamine synthetase, as opposed to 14-30 min with 1 unit of glutamate dehydrogenases from various sources. The present method was used to determine ammonia in serum, microbiol-culture broth, and waste water. The method can be modified for spectrophotometry in the visible region by substituting pyruvate oxidase, peroxidase, and appropriate chromogens for lactate dehydrogenase and NADH. With 4-aminoantipyrine (4AA) and phenol, and with 4AA and N-ethyl-N-2-hydroxyethyl-m-toluidine as chromogens, the sensitivity of ammonia determination was 0.65 and 1.7 times that with glutamate dehydrogenase, respectively. The present method was also applicable to the continuous detection of the activity of some ammonia-forming enzymes such as guanase, adenosine deaminase, and urease and to the determination of 0.5-30 microM ATP-ADP after some modification of the mixture.
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PMID:A rapid assay method for ammonia using glutamine synthetase from glutamate-producing bacteria. 288 29