Molecular dynamic simulation study of cholesterol and conjugated double bonds in lipid bilayers

• Published in: Chemistry and physics of lipids Vol. 164; no. 8; pp. 811 - 818
• Main Authors: Zhao, Guijun, Subbaiah, P.V., Mintzer, Evan, Chiu, See-Wing, Jakobsson, Eric, Scott, H.L.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.11.2011
• Subjects: anticarcinogenic activity; Cholesterol; Cholesterol - chemistry; Computer Simulation; conjugated linoleic acid; Conjugated linoleic acids; dairy products; isomers; Linoleic Acids, Conjugated - chemistry; lipid bilayers; Lipid Bilayers - chemistry; Molecular dynamic simulation; molecular dynamics; Molecular Dynamics Simulation; phosphatidylcholines; Conjugated linoleic acids; Cholesterol; Molecular dynamic simulation
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/j.chemphyslip.2011.09.008

► Two isomers of a conjugated linoleic acid have different biological effects. ► We find that the effect of cholesterol on structure of the bilayers of the two isomers is very similar. ► One major difference lies in the order parameter profile for the unsaturated bond. ► Another major difference lies in the radial distribution profile of lipids around cholesterols. Conjugated linoleic acids (CLA) are found naturally in dairy products. Two isomers of CLA, that differ only in the location of cis and trans double bonds, are found to have distinct and different biological effects. The cis 9 trans 11 (C9T11) isomer is believed to have anti-carcinogenic effects, while the trans 10 cis 12 (T10C12) isomer is believed to be associated with anti-obesity effects. In this paper we extend earlier molecular dynamics (MD) simulations of pure CLA–phosphatidylcholine bilayers to investigate the comparative effects of cholesterol on bilayers composed of the two respective isomers. Simulations of phosphatidylcholine lipid bilayers in which the sn-2 chains contained one of the two isomers of CLA were performed in which, for each isomer, the simulated bilayers contained 10% and 30% cholesterol (Chol). From MD trajectories we calculate and compare structural properties of the bilayers, including areas per molecule, thickness of bilayers, tilt angle of cholesterols, order parameter profiles, and one and two-dimensional radial distribution function (RDF), as functions of Chol concentration. While the structural effect of cholesterol is approximately the same for both isomers, we find differences at an atomistic level in order parameter profiles and in two-dimensional radial distribution functions.