NAD+

NAD+ has been examined extensively in cell-free biochemistry and cultured-cell systems as the electron carrier that couples catabolic dehydrogenase reactions to downstream metabolism. In these research settings it is a standard substrate for enzymes such as lactate dehydrogenase, alcohol dehydrogenase, and the glyceraldehyde-3-phosphate dehydrogenase step of glycolysis, where the NAD+/NADH ratio is used as a readout of cellular redox state.

Beyond its classical redox role, NAD+ has been studied preclinically as a consumed co-substrate rather than a recycled cofactor. Investigators have used it to probe the activity of sirtuin deacylases and poly(ADP-ribose) polymerases (PARPs), both of which cleave NAD+ and release nicotinamide during their catalytic cycles. It also serves as a precursor for signaling molecules including cyclic ADP-ribose. This body of work remains preliminary and ongoing, and the content here describes laboratory observations only; it is not medical advice and implies no health outcome.