Mitochondria catalyze the reduction of NAD by reduced methylviologen

Abstract
Mitochondria from beef heart and yeast catalyze the reduction of NAD to NADH at the expense of reduced methylviologen (MV+). Based on protein the specific activity of mitochondria for this reaction is about 10–20‐times higher than the consumption of oxygen in the presence of succinate or NADH. In 2H2O buffer (4S)‐[4‐2H]NADH is formed in high enantiomeric excess if the reduced methylviologen is electrochemically regenerated.