Cyanide--an uncompetitive inhibitor of NAD(P)-dependent malic enzyme from human term placental mitochondria.

The activity of NAD(P)-dependent mitochondrial malic enzyme was considerably inhibited by KCN, whereas under the same conditions azide affected the enzyme only slightly. Kinetic studies showed that KCN is an uncompetitive inhibitor of mitochondrial malic enzyme from human placenta. In contrast to the mitochondrial enzyme, the cytosolic malic enzyme was only slightly affected by KCN and under the same conditions the effect of azide was negligible. The effect of KCN was compared to this on the malic enzyme from other sources.