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Title: One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis]

Abstract

One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10/sup 5/ to 10/sup 8/ M/sup -1/ s/sup -1/, depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH/sup +/.). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine)/sup +/. were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10/sup 4/ to 10/sup 5/ M/sup -1/ s/sup -1/, so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appearsmore » to be an unlikely process. 1 table.« less

Authors:
 [1]; ; ;
  1. Univ. of Notre Dame, IN
Publication Date:
OSTI Identifier:
5779709
Resource Type:
Journal Article
Journal Name:
J. Phys. Chem.; (United States)
Additional Journal Information:
Journal Volume: 87:16
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHLORPROMAZINE; RADIOLYSIS; DEUTERIUM; ISOTOPIC EXCHANGE; NAD; LABELLING; PHENOL; WATER; AQUEOUS SOLUTIONS; CATIONS; CHEMICAL REACTION KINETICS; DEUTERIUM COMPOUNDS; ELECTRON TRANSFER; EXPERIMENTAL DATA; OXIDATION; PH VALUE; PHENOXY RADICALS; PULSED IRRADIATION; REDUCTION; AMINES; AROMATICS; AZINES; CENTRAL NERVOUS SYSTEM AGENTS; CENTRAL NERVOUS SYSTEM DEPRESSANTS; CHARGED PARTICLES; CHEMICAL RADIATION EFFECTS; CHEMICAL REACTIONS; CHEMISTRY; COENZYMES; DATA; DECOMPOSITION; DISPERSIONS; DRUGS; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; HYDROGEN ISOTOPES; HYDROXY COMPOUNDS; HYPNOTICS AND SEDATIVES; INFORMATION; IONS; IRRADIATION; ISOTOPES; KINETICS; LIGHT NUCLEI; MIXTURES; NUCLEI; NUCLEOTIDES; NUMERICAL DATA; ODD-ODD NUCLEI; ORGANIC CHLORINE COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXYGEN COMPOUNDS; PHENOLS; PHENOTHIAZINES; PSYCHOTROPIC DRUGS; RADIATION CHEMISTRY; RADIATION EFFECTS; RADICALS; REACTION KINETICS; SOLUTIONS; STABLE ISOTOPES; TRANQUILIZERS; 400600* - Radiation Chemistry; 400303 - Organic Chemistry- Isotope Exchange & Isotope Separation- (-1987); 400302 - Organic Chemistry- Isotope Effects- (-1987)

Citation Formats

Grodkowski, J, Neta, P, Carlson, B W, and Miller, L. One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis]. United States: N. p., 1983. Web. doi:10.1021/j100239a035.
Grodkowski, J, Neta, P, Carlson, B W, & Miller, L. One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis]. United States. https://doi.org/10.1021/j100239a035
Grodkowski, J, Neta, P, Carlson, B W, and Miller, L. Thu . "One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis]". United States. https://doi.org/10.1021/j100239a035.
@article{osti_5779709,
title = {One-electron transfer reactions of the couple NAD. /NADH. [Pulse radiolysis]},
author = {Grodkowski, J and Neta, P and Carlson, B W and Miller, L},
abstractNote = {One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10/sup 5/ to 10/sup 8/ M/sup -1/ s/sup -1/, depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH/sup +/.). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine)/sup +/. were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10/sup 4/ to 10/sup 5/ M/sup -1/ s/sup -1/, so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appears to be an unlikely process. 1 table.},
doi = {10.1021/j100239a035},
url = {https://www.osti.gov/biblio/5779709}, journal = {J. Phys. Chem.; (United States)},
number = ,
volume = 87:16,
place = {United States},
year = {1983},
month = {8}
}