Section 31
Chapter 30,019

An enzymatic method for determination of 1 -lactic acid

Pfleiderer, G.; Dose, K.

Biochemische Zeitschrift 326(6): 436-441


ISSN/ISBN: 0366-0753
Accession: 030018628

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A diphosphopyridine nucleotide (DPN)-linked lactic dehydrogenase is used, and the amount of reduced diphosphopyridine nucleotide (DPNH) that is formed from oxidation of lactic acid is measured. To shift the equilibrium in favor of DPNH formation, the reaction mixture is adjusted to pH 9.7 with carbonate-bicarbonate buffer, and a large excess of DPN is used. The lactic acid originally present is then calculated by the equation: lactic acid = K[image]X [DPNH]2 + [DPNH], where K[image] = the mean value for the equilibrium constant of the reaction. The method is highly specific and accurate for 1 (+)-lactic acid in amounts between 3 and 35mg. The presence of pyruvic acid in the starting material in amounts greater than 1.5% of the amount of lactic acid present interferes with the reaction and requires a correction factor described by the authors.

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