Determination of Serum Creatinine by Enzymatic Method

概要

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A new method is described for determining the concerltration of creatinine (and also of creatine) in human serum. The method consists of enzymatic conversion of creatinine to formaldehyde via creatine and sarcosine.<BR>The first enzyme involved is creatinine amidohydrolase (creatininase) which reversively converts creatinine to creatine. The second enzyme is creatine amidinohydrolsae (creatinase) that gives sarcosine from creatine, the third enzyme being sarcosine dehydrogenase by whic sarcosine is converted to glycine and formaldehyde. The formaldehyde produced is determined by measuring the color intensity of red purple tetrazine caused by the reaction of HCHO with AHMT (4-amino-3-hydrazino-1, 2, 4-triazole) in the presence of KlO<SUB>4</SUB> at alkaline region. Only a 0.1ml of serum is enough to measure the conterlt of creatinirle, and deproteinization proCedure is unnecessary. Linear relationship was observed between the intensity of absorbance and the concentration of creatinine. The comparison of the results obtained by the Folin method with those by the present one gave a value of 0.992 as the correlation coefficient (r).