Studies on Squalene Epoxidase of Rat Liver*
ثبت نشده
چکیده
Rat liver microsomes previously heated to 50” for 5 mm accumulate 2,3-oxidosqualene on incubation with squalene. Squalene epoxidase activity can be assayed either with squalene and heated microsomes or with lO,ll-dihydrosqualene and intact microsomes. In common with other monooxygenases, the epoxidase requires TPNH and molecular oxygen. Both a soluble fraction of rat liver and microsomes are necessary for enzyme activity. Carbon monoxide or potassium cyanide fall to inhibit squalene epoxidation.
منابع مشابه
Studies on squalene epoxidase of rat liver.
Rat liver microsomes previously heated to 50” for 5 mm accumulate 2,3-oxidosqualene on incubation with squalene. Squalene epoxidase activity can be assayed either with squalene and heated microsomes or with lO,ll-dihydrosqualene and intact microsomes. In common with other monooxygenases, the epoxidase requires TPNH and molecular oxygen. Both a soluble fraction of rat liver and microsomes are ne...
متن کاملRegulation of squalene epoxidase activity and comparison of catalytic properties of rat liver and Chinese hamster ovary cell-derived enzymes.
Squalene epoxidase activity has been studied in cell-free preparations of Chinese hamster ovary (CHO) cells and rat liver. In contrast to rat liver microsomal squalene epoxidase, the enzyme of CHO cells is only slightly activated by the autologous cytosolic fraction, whereas phosphatidylglycerol or rat liver cytosolic preparations are potent stimulators of this enzyme. Triton X-100, a known sti...
متن کاملRegulation of squalene epoxidase activity in rat liver.
Regulation of squalene epoxidase activity was examined in rat hepatic microsomes. The hepatic squalene epoxidase activity was high in the dark period and low in the light period. Three percent cholestyramine feeding increased the hepatic squalene epoxidase activity by 2.5-fold, and the administration of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, incre...
متن کاملRegulation of squalene epoxidase in HepG2 cells.
Regulation of squalene epoxidase in the cholesterol biosynthetic pathway was studied in a human hepatoma cell line, HepG2 cells. Since the squalene epoxidase activity in cell homogenates was found to be stimulated by the addition of Triton X-100, enzyme activity was determined in the presence of this detergent. Incubation of HepG2 cells for 18 h with L-654,969, a potent competitive inhibitor of...
متن کاملSqualene Epoxidase of Rat Liver*
The microsomal enzyme system from rat liver which catalyzes the epoxidation of squalene to 2,3-oxidosqualene (squalene epoxidase) has been investigated further with 10 ,ll-dihydrosqualene as the artacial substrate. Liver supernatant contributes two essential components to the epoxidase system, one heat stable and the other heat labile (YAMAMOTO, S., AND BLOCH, K. (1970) J. Biol. Chem. 245, 1670...
متن کامل