Regeneration of NAD

jmol3d.gif NAD (nicotinamide adenine dinucleotide) is a hydrogen acceptor, and as a result of accepting 2 hydrogen atoms its molecule becomes reduced.
It participates in many dehydrogenation reactions (effectively a type of oxidation), and is a co-factor in many dehydrogenase enzymes, e.g. succinate dehydrogenase.

It is thus able to reduce other compounds by passing on the hydrogen as hydrogen ions (protons) and electrons.

NAD then becomes available to accept more hydrogens and continues the process, which would otherwise come to a halt.

The various reactions of respiration interact with one another in a controlled way to keep going the cycle of usage of NAD to remove and pass on hydrogens.


Sometimes NAD is written as NAD+, and its reduced form as NADH/H+ (or NADH or NADH2)