New Measurement of NADH Determined as Oxygen Consumption or H2O2 Formation in the Presence of Electron Carrier:I. Determination of LDH Activity by New Measurement Method

概要

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When various concentrations of an authentic NADH were added to a solution of 1-methoxy-5-methylphenazium methylsulfate in a sealed vessel equipped with an oxygen electrode, O2 in the mixture was consumed in proportion to concentrations of NADH added.Conversely, it was possible to make a quantitative estimate of the amount of NADH by measuring O2 consumption in this reaction system. In addition, H2O2 was also produced in the reaction system. The amount produced, determined colorimetrically using peroxidase with 4-aminoantipyrine and ADOS as chromogens, was also equivalent to that of NADH added. Although keeping the reaction solution, which contained a pigment formed, at room temperature led to a rapid discoloration, this discoloration was inhibited by addition of superoxide dismutase. On the basis of the above results, LDH was assayed by measuring O2 consumption or H2O2 production in the enzymatic reaction using lactate as substrate. The activity obtained by the present method, especially in the case of NADH measurement by means of O2consumption, showed a good correlation with that obtained by the UV method, indicating that this is a valid new LDH assay method.
Japan Society of Clinical Chemistryの論文