| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject reagent for use in e.g. determining urea-nitrogen useful in e.g. the clinical examination for various renal function disorders and hepatic parenchymal disorders, by formulating a urease solution with a chelating agent and a surfactant and others so as to maintain enzyme activity for a long period. SOLUTION: Determination of urea-nitrogen in a biological sample such as serum or urine is carried out according to the following procedure: a reagent comprisingα-ketoglutaric acid, NAD(P)H (reduced-type nicotinamidoadenine dinucleotide (phosphate)) and a glutamic acid dehydrogenase is first added to a sample followed by addition of a urease liquid reagent to hydrolyze the urea in the sample with urease to form ammonia, the rate of formation of the ammonia is determined based on the rate of decrease in the NAD(P)H, and the aimed urea-nitrogen is quantified based on the above rate of decrease in the NAD(P)H. The whole reagent used in the above determination is formulated with a chelating agent and/or surfactant so as to maintain high enzyme activity for a long time in the solution with high long-term storage stability, thus affording the objective urease liquid reagent.
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