Transient species in the stepwise interconversion of NADH and NAD+.
Two mechanisms of the interconversion of NADH and NAD+ in the coenzyme itself and in its analogues are discussed: a one-step hydride transfer and a stepwise electron-proton-electron transfer. Direct characterization of the transient species in the stepwise process and inversion of the stability order of the keto and enol tautomers is presented. The nonenzymatic and enzyme-mediated reactions of selected pyridinium salts that affect the NADH <==>NAD+ equilibrium are discussed in terms of their potential cytotoxicity.
Gebicki
Jerzy
J
Institute of Applied Radiation Chemistry, Technical University, 90-924 Lodz, Poland.
Marcinek
Andrzej
A
Zielonka
Jacek
J
D000818:Animals; D002412:Cations / Q000737:chemistry / Q000378:metabolism; D005609:Free Radicals; D006801:Humans; D009243:NAD / Q000737:chemistry / Q000378:metabolism*
D002412:Cations; D005609:Free Radicals; D009243:NAD