title: Interaction of two oxysterols, 7-ketocholesterol and 25-hydroxycholesterol, with phosphatidylcholine and sphingomyelin in model membranes.
abstract: Oxidized analogs of cholesterol (oxysterols) are produced through both enzymatic and non-enzymatic pathways and have been shown to perturb membrane properties in vitro and in vivo. In the present study, the membrane behavior of two naturally occurring oxysterols, 25-hydroxycholesterol and 7-ketocholesterol, was examined in two model systems. The presence of an additional oxygen moiety was found to alter membrane properties compared to native cholesterol and to each other in lipid monolayers, composed of either pure sterol or sterol-glycerophospholipid and sterol-sphingomyelin binary films, as well as in mixed multilamellar vesicles. The ability of oxysterols to condense phosphatidylcholine and sphingomyelin films, their capacity to cause changes in in-plane elasticity moduli, and their propensity to form detergent-resistant membrane domains were all found to be dependant on the location of the oxygen functionality in the oxysterol, the chemical nature of the phospholipid in the model systems, and the oxysterol/phospholipid ratio in the membrane. The findings described in this study with respect to their biophysical/biophysiological implications provide additional insight into the activity of cytotoxic oxysterols in model membranes.
authors.affiliation: Department of Chemistry and Biochemistry, Stern College for Women, Yeshiva University, 245 Lexington Avenue, New York, NY 10016, United States. mintzer@yu.edu
authors.forename: Evan
authors.initials: E
authors.lastname: Mintzer
authors.forename: Grace
authors.initials: G
authors.lastname: Charles
authors.forename: Sharon
authors.initials: S
authors.lastname: Gordon
mesh_terms: D006888:Hydroxycholesterols / Q000737:chemistry*; D007653:Ketocholesterols / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D010713:Phosphatidylcholines / Q000737:chemistry*; D012995:Solubility; D013109:Sphingomyelins / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D006888:Hydroxycholesterols; D007653:Ketocholesterols; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D013501:Surface-Active Agents; C007997:25-hydroxycholesterol; C003001:7-ketocholesterol