NAD+ is the oxidized dinucleotide cofactor itself, whereas compounds such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) participate in NAD+ biosynthetic pathways. This distinction makes NAD+ a useful research tool for investigating NAD+-dependent enzymatic reactions, cofactor utilization mechanisms, redox system dynamics, and the biochemical relationships between NAD+ and precursor-associated pathways.

NAD+ serves as an obligate substrate for three major enzyme families: poly(ADP-ribose) polymerases (PARPs), sirtuins (SIRT1–7), and CD38/CD157 ADP-ribosyl cyclases. These enzymes utilize NAD+ in processes involving protein modification, enzymatic regulation, signal transduction, and cofactor-dependent biochemical activity.

Their dependence on NAD+ has made them important targets for investigations of enzyme-cofactor interactions and NAD+-associated regulatory mechanisms.

NAD+ occupies a central role in both redox chemistry and enzyme-mediated regulatory systems. In addition to functioning as a reversible electron carrier, it participates directly in the catalytic activity of multiple NAD+-dependent enzyme families.

These characteristics have established NAD+ as a valuable research tool for investigating redox biology, enzyme kinetics, cofactor-dependent catalysis, sirtuin pharmacology, PARP biochemistry, CD38-associated pathways, and the molecular mechanisms governing NAD+-dependent biochemical processes.