Cholesterol effects on a mixed-chain phosphatidylcholine bilayer: a molecular dynamics simulation study

A molecular dynamics simulation of a mono- cis-unsaturated 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer containing ~22 mol% of cholesterol (POPC-Chol) was carried out for 15 ns. An 8-ns trajectory was analysed to determine the effects of Chol on the membrane properties and compare it with that o...

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Bibliographic Details
Published in:Biochimie 2006-05, Vol.88 (5), p.449-460
Main Authors: Róg, T., Pasenkiewicz-Gierula, M.
Format: Article
Language:English
Subjects:
Chain order
Chain packing
Chain tilt
Cholesterol - chemistry
Cholesterol α-face
Cholesterol β-face
Cis double bond
Computer Simulation
Dimyristoylphosphatidylcholine - chemistry
Dimyristoylphosphatidylcholine - metabolism
Hydrogen Bonding
Kinetics
Lipid Bilayers - chemistry
Membrane Fluidity
Models, Molecular
Molecular Conformation
Phosphatidylcholine
Phosphatidylcholines - chemistry
Phosphatidylcholines - metabolism
Static Electricity
Thermodynamics
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Summary:A molecular dynamics simulation of a mono- cis-unsaturated 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer containing ~22 mol% of cholesterol (POPC-Chol) was carried out for 15 ns. An 8-ns trajectory was analysed to determine the effects of Chol on the membrane properties and compare it with that on the fully saturated 1,2-dimyristoyl-phosphatidylcholine bilayer containing ~22 mol% of Chol (DMPC-Chol). The study suggests that the experimentally observed weaker effect of Chol on the POPC than DMPC bilayer might result from a different vertical localisation of the Chol hydroxyl group (OH-Chol) in both bilayers: in the POPC-Chol bilayer, OH-Chol is placed ~3 Å higher in the bilayer interface than in the DMPC-Chol bilayer. Because of the rigid cis double bond in the β-chain of POPC, Chol fits worse to the POPC-Chol membrane environment and is pushed up, in effect all Chol ring atoms are, on average, located above the double bond. Both in mono- cis-unsaturated and fully saturated PC bilayers, Chol induces stronger van der Waals interactions among the chains, whereas its interactions with the chains are weak. In contrast to DMPC, the smooth α-face of the Chol ring lowers the order of POPC chains, whereas the rough β-face increases the order.
ISSN:0300-9084
1638-6183
DOI:10.1016/j.biochi.2005.10.005