The oxidation-reduction potential of coenzyme I

The oxidation-reduction potential of cozymase (diphosphopyridine nucleotide) was calculated from the free energies of formation of aqueous d-alanine and d-glutamic acid based on thermal data, and the equilibria measured by Wurmser and Filitti-Wurmser(1) for pyruvate + 2H+ + 2(e) ⇌ alanine + H2O, by Cohen(2) for α-ketoglutarate + alanine ⇌ d-glutamate and pyruvate, and by von Euler et al.(3) for the reaction α-ketoglutarate + NH+4 + reduced cozymase ⇌ glutamate + oxidized cozymase. The value for the potential so calculated is at 30° E'0 = -0.072 - 0.03 pH ± 0.0008 volt.