Study of the electrochemical oxidation of reduced nicotinamide adenine dinucleotide.

The electrochemical reduction of pyrimidine and certain derivatives was investigated over the normal pH range by polarography, coulometry, and macroscale electrolysis. The reduction products were examined chemically, polarographically, and spectrophotometrically. Pyrimidine is first reduced at the 3,4 position in a le process to a free radical, which may dimerize or be reduced (le process) to 3,4-dihydropyrimidine; the latter can be further reduced (2e process) to tetrahydropyrimidine. The 2-amino- and 2-amino-4- methylpyrimidines are reduced in two le steps, first to a free radical and then to the 3,4-dihydro derivative. 4-Amino-2,6-dimethylpyrimidine gives a single 4e wave, which likeIy involves 2e reduction to the 3,4-dihydro compound followed by deamination to 2,6-dimethylpyrimi dine, which is reduced (2e prccess) to 2,6- dimethyl-3,4dihydropyrimidine. Cytosine (4-amino-2-hydroxypyrimidine) undergoes a 3e reduction, which involves 2e reduction of the 3,4 N = C bond, deamination to form 2-hydroxyPyrimidine and le reduction of the latter to a free radical which dimerizes. 2-Hydroxypyrimidine itself shows only le reduction. The dihydro and tetrahydro products are unstable in aqueous solution; pseudo first-order rate of disappearance is shown by the two compounds examined. In general, 4-amino- pyrimidines having the 3,4 position hydrogenated deaminate readily to generate the reducible 3,4 N = C bond. (auth)

ELECTROCHEMICAL REDUCTION OF PYRIMIDINE, CYTOSINE AND RELATED COMPOUNDS: POLAROGRAPHY AND MACROSCALE ELECTROLYSIS. Report No. 63

The sections in this article are


Introduction
NAD(P)+/NAD(P) in Living Systems
Formal Potential of the NAD+/NADH Redox Couple
Focus and Scope of the Chapter


Direct Electrochemical Oxidation of NAD(P)H
General Observations
Effect of Adsorption
Mechanism and Kinetics


Homogeneous Oxidation of NAD(P)H by Oxidizing Redox Compounds
One-electron No-proton Acceptors
Two-electron-proton Acceptors
o-quinones and p-quinones
Aromatic Diimines




Electrocatalytic Oxidation of NAD(P)H at Mediator-modified Electrodes
General Remarks of CMEs
o-Quinones and Phenylenediimine Derivatives


Other Mediating Functionalities and Metal-coated Electrodes
Catalytic NADH Oxidation at CMEs Based on Polymers
Mechanistic and Kinetic Aspects


CMEs Based on NADH-oxidizing Enzymes
Amperometric Biosensors Based on NAD(P)-dependent Dehydrogenase Enzymes
Direct Electrochemical Reduction of NAD(P)+
General Observations
Adsorption Phenomena
Mechanism and Kinetics


Electrocatalytic Reduction of NAD(P)+
Nonenzymatic Electroreduction of NAD(P)+
Enzymatic Electroreduction of NAD(P)+


Acknowledgment

Electrochemistry of NAD(P)+/NAD(P)H

Normal pulse polarographic analysis based on mercury anodization. Sulfide and iodide

I. INTRODUCTION The senior author and his collaborators have long been concerned with the use of analytical chemical techniques – more specifically, experimental approaches and methodologies primarily based on polarography – to study problems of general chemical interest. Currently, electroanalytical approaches are being used in a systematic investigation of chemical phenomena involving biologically significant compounds, where such approaches seem to offer distinct advantages. Attention has been focused on the behavior of nucleic acid components, pyridine coenzymes, and relevant model compounds in solution as well as the electron-transfer interface. Behavior at the interface involves (a) adsorption of original, intermediate, and product species, (b) association in the adsorbed state, (c) mechanisms and kinetics of electron-transfer (redox) processes, and (d) chemical reactions (kinetics and mechanisms) involving reactant, intermediate (free radical, carbanion), and product species preceding, accompanying...

Nicotinamide-Nad Sequence: Redox Processes and Related Behavior: Behavior and Properties of Intermediate and Final Products

The reduction behavior of N1-methyl nicotinamide iodide has been studied by drop-time controlled polarography In highly acidic media (below pH 3) two pH dependent waves were observed (I and I′) the latter having an abnormally high limiting current In the pH range of 3–10, two waves were observed (II and III), the former being pH-independent whereas the E 1/2 of the latter shifted — 60 mV per pH unit Evidence is presented for a chemical association step, possibly a dimerization occurring between reduction steps II and III Reoxidation of the reduction product of wave II was obtained at 740 mV above the potential of the wave II by cyclic voltammetry on stationary vitreous carbon electrodes This reoxidation peak is also pH independent

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Electrochemical Properties of Model Compounds of Nicotinamide-adenine-dinucleotide in Aqueous Solution

Taking into account the biological significance of electron-exchange properties of nucleic heterocycles, we have studied the electrochemical reduction of their simplest model compound ie the pyrimidine, using drop-time controlled polarography and cyclic voltammetry on mercury drop and stationary vitreous carbon electrode The characteristics of the different reduction waves have been studied with respect to the different experimental parameters: pH, nature and concentration of buffer solutions, pyrimidine concentration, mercury flow and mechanically controlled drop-time, temperature, nature of the electrode, etc The analysis of the experimental data is discussed in terms of energetical significance of the phenomena observed Evidence is given of a chemical association step, possibly a dimerization, occuring between the two reduction steps in acid media

https://hal-enpc.archives-ouvertes.fr/hal-01096398/document

Gilbert Hammouya

Papers

Electrochemical Properties of Model Compounds of Nicotinamide-adenine-dinucleotide in Aqueous Solution

Electrochemical Properties of Model Compounds of Nucleic Heterocycles in Aqueous Solutions