Figure 1.

Diagram of proposed transplasma membrane NADH oxidizing enzymes.

Notes: The NADH oxidase involves NADH b5 reductase or NQ0-1 to reduce coenzyme Q, which is oxidized by reduced CoQ oxidase (ENOX) to make CoQ and H₂O. Transferrin can stimulate the oxidase. The VDAC porin transfers electrons from internal NADH to ferricyanide carried by thiol groups in the channel. Coenzyme Q is involved in the electron transfer but its site of action is not known. It may float in the lipid bilayer or be bound to the protein. The NAD⁺ formed could activate sirtuin to activate transcription. NQ0-1 can oxidize NADH or NADPH.

Abbreviations: CoQ, Coenzyme Q; NADH, nicotinamide adenine dinucleotide reduced; VDAC, voltage dependent anion channel; NADPH, nicotinamide adenine dinucleotide phosphate reduced; SH, sulphydryl (or thiol) group; NAD, nicotinamide adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate.