Abstract
1) NADH-cytochrome c reductase activity in membrane was inhibited by p-chlo romercuric benzoate and N-ethylmaleimide, but not by KCN, NaN3, Antimycin A or rotenone.
2) Both NADH-cytochrome c reductase and NADH-ferricyanide dehydrogenase located in the membrane and microsome showed the same Km value respectively. These Km values were retained unchanged even in case of CCl4 treatment in vivo.
3) Membrane also contained cytochrome b5 and P-450, of which contents were much lower than those in microsome. CCl4, however, resulted in an increase of these heme proteins to twice in membrane, but a decrease to half in microsome.
4) NADH-cytochrome b5 reductase activity was only one third of NADH-cytochrome c reductase activity in membrane irrespective of CCl4 administration in vivo.
5) It is proposed that NADH-cytochrome c reductase in membrane orignates from microsome, but not from mitochondria, and that increase of enzyme activity after CCl4 administration may be caused by migration of heme- and flavo-proteins from endoplasmic reticulum to plasma membranes of liver cells in vivo.
