Reduction by a model of NAD(P)H. XIV. Mechanistic consideration on the role of metal ion.

The driving force for the catalytic activity of metal ions on the reduction of α-keto esters with an NAD(P)H-model compound has been discussed. The scope of the reaction and spectroscopic investigations as well as molecular orbital consideration have revealed that the transition state of the reaction consists of a ternary complex in analogy with a coenzyme–enzye–substrate complex in an enzymic system. It is concluded that, at the transition state, one electron migrates from a model compound to a substrate through a metal ion, which is followed by the transfer of a proton.