Nonenzymic hydrogen transfer between reduced and oxidized pyridine nucleotides.

Mixtures of NADH and NADP+ or NADPH and NAD+ were incubated and periodically assayed for hydrogen transfer by measuring the formation of NADPH and NADH with glutathione reductase (NAD(P)H: oxidized-glutathione oxidoreductase, EC 1.6.4.2) and lactate dehydrogenase (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27), respectively. Each mixture showed a steady nonenzymic transfer of hydrogen from the reduced to the oxidized pyridine nucleotide to yield a product that was completely enzymically active. The results demonstrate the specific nonenzymic transfer of hydrogen from NADH and NADPH to the pyridine C-4 position of NADP+ and NAD+, respectively.