Page - (000047) - in Biomedical Chemistry: Current Trends and Developments

oxidation reaction occurs in just one step: as a base captures the proton attached to the oxygen atom, a hydride is transferred to NAD+ and the carbonyl group is generated (Scheme 1.1.32). The hydride transfer is a simple conjugate nucleophilic addition, as the ion is a strong nucleophile. The reduction reaction is simply the reverse of the oxidation process (Scheme 1.1.33). Figure 1.1.7: Structure of NAD+ and NADH. The structures of NADP+ and NADPH are identical with exception of the highlighted hydroxyl group (in magenta), which is replaced by a phosphate group. Scheme 1.1.32: Mechanism of an alcohol oxidation by NAD+ or NADP+ ‒ the base may be provided by residues of an enzyme. Scheme 1.1.33: Mechanism of an alcohol reduction of a carbonyl group by NAD or NADP, in this case of an acetylated acyl carrier protein (ACP), an important part in the fatty acid synthesis.