title: Thermodynamic properties of the cholesterol transfer reaction from liposomes to cytochrome P450scc: an enthalpy-entropy compensation effect.
abstract: We have investigated the thermodynamic properties of the cholesterol transfer reaction from various types of liposomes to purified steroid-free cytochrome P450scc. From the results of temperature effect on the reaction, we obtained delta G+, delta H+, and delta S+ values for the reaction with various phosphatidylcholine vesicles containing different fatty acyl chains. The plots of delta H+ against delta S+, and delta G+ against delta H+ both reveal that an enthalpy-entropy compensation effect was seen in a series of phospholipid and micellar media of cholesterol. Our beta-value of 420 degrees K is unusually high among reported values for biochemical reactions.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology; D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism*; D008823:Micelles; D010713:Phosphatidylcholines / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D005227:Fatty Acids; D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol