Thermotropic behaviour of phospholipid vesicles reconstituted with rat liver microsomal cytochrome P-450.
The interaction of rat liver microsomal cytochrome P-450 with phospholipids has been investigated employing differential scanning microcalorimetry. It is shown that the thermotropic behaviour of phospholipid vesicles reconstituted with cytochrome P-450 depends on liposome composition, protein concentration and the mode of reconstituted system preparation. From the delta H dependence on protein concentration in proteoliposomes it was calculated that one cytochrome P-450 molecule influence 350 +/- 50 dimyristoylphosphatidylcholine (DMPC) molecules. The electrostatic interaction of cytochrome P-450 and negatively charged phospholipid, phosphatidylinositol (PI), mixed with DMPC involves the temperature stabilization of proteoliposomes at a phase transition of phospholipid bilayers. The thermal denaturation temperature is increased due to negatively charged PI added.
D000818:Animals; D002152:Calorimetry, Differential Scanning; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004134:Dimyristoylphosphatidylcholine; D007700:Kinetics; D008081:Liposomes; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010743:Phospholipids / Q000494:pharmacology*; D011510:Proteolipids; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
D008081:Liposomes; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010743:Phospholipids; D011510:Proteolipids; C020485:proteoliposomes; D003577:Cytochrome P-450 Enzyme System; D004134:Dimyristoylphosphatidylcholine