Energetics of the one-electron steps in the NAD+/NADH redox couple

The one-electron reduction potential of NAD+ has been determined using pulse radiolysis to study electron-transfer equilibria between it and a low potential bipyridylium compound. The determined value E1 electron pH7 (NAD+/NAD) = -922 +/- 8 mV (NHE scale) is used to calculate E2 electrons pH7 (NAD/NADH) = +282 mV. E1 electron pH7 for 1-methylnicotinamide, E1 electron pH7 (MeN+/MeN) = -918 +/- 7 mV.