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

Abstract

Illustrations of the application of analytical chemical techniques to the study of chemical phenomena are given. In particular, electrochemical techniques and methodology and, to a lesser extent, spectrophotometry were used to investigate the solution behavior, adsorption, redox processes including coupled chemical reactions, and allied aspects of biologically significant compounds and of their intermediate and final redox products, e.g., the behavior of the free radicals produced by initial one-electron processes. This approach is illustrated by the consideration of the behavior in aqueous and nonaqueous media of a sequence of compounds ranging from nicotinamide (3-carbamoylpyridine) to NAD/sup +/ and NADP/sup +/; the latter compounds function as coenzymes for the pyridinoproteins which are principal components in the Krebs citric acid cycle and in the electron transport chain in biological redox reactions. The discussion is presented under the following section headings: interpretation of electrochemical behavior; mechanistic patterns; kinetic aspects of charge-transfer and chemical reactions; correlation with theoretically calculated parameters; and, mechanisms of biological oxidation-reduction reactions. The use of pulse radiolysis, chronopotentiometric, and cyclic voltammetric methods in studies on free radical dimerization rates is reviewed in the discussion of the kinetic aspects of charge-transfer and chemical reactions. (188 references) (JGB)