Effects of oxygenated sterol on phospholipid bilayer properties: a molecular dynamics simulation

The properties of dipalmitoylphosphatidylcholine (DPPC):6-ketocholestanol bilayer at 50 mol% sterol were studied using the molecular dynamics simulation technique. Our simulations were performed at constant pressure and temperature on a nanosecond time scale. Data from this simulation were compared to the results of our previous simulations on DPPC and DPPC-cholesterol bilayers. We conclude that the differences in the properties of membranes with cholesterol and ketocholestanol are due to the difference in 6-ketocholestanol and cholesterol location in the bilayer. The presence of the keto group in ketocholestanol moves the sterol towards the polar region closer to interface with water. We predict that similar mechanisms would govern the properties of membranes with other oxygenated sterols, such as for example 7-ketocholesterol. Results of our simulations are in a good agreement with the data available from the experiment.