Membrane Structure I

2047-Pos

Effect of peroxidation on the properties of a palmitoyl-2-linoleyl-sn-glycero-3-phosphatidylcholine bilayer

Halls A/B/C/D

3E Membrane Structure

Jirasak Wong-ekkabut¹, Luca Monticelli², Zhitao Xu², Svetlana Baoukina², Wannapong Triampo¹, I Ming Tang¹, Peter Tieleman².
¹Department of Physics, Faculty of sciences, Mahidol University, Bangkok, Thailand, ²Department of Biological sciences, University of Calgary, Calgary, AB, Canada.

427a

Lipid peroxidation plays an important role in cell membrane damage. Polyunsaturated lipids are the main target of oxidation by free radicals. We studied 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC) lipid bilayers and focused on 4 main products of lipid peroxidation, including oxidized chains with either a hydroperoxide or an aldehyde group and with different length: 9tc-hydroperoxide linoleic acid, 13tc-hydroperoxide linoleic acid, 9-oxononanoic acid, and 12-oxo-9-didecadienoic acid. We used molecular dynamics simulations to investigate the effect of lipid peroxidation on the properties of PLPC lipid bilayers as a function of the concentration of oxidized lipids, with concentrations from 1 to 50% for each of the oxidation products.
For all oxidized lipids, the area per lipid increases and the bilayer thickness decreases with increasing concentrations of oxidized lipid. Both the area per lipid and its thickness depend on the position of the oxygen atom in the lipid tail, and the thickness also depends on the length of the oxidized lipid tail. The deuterium order parameter in the oxidized tails is substantially decreased at positions before the peroxide and aldehyde groups. Water defects are observed in the bilayers more frequently as the concentration of the oxidized lipids is increased. The changes in the area per lipid, the thickness, deuterium order parameters and the water permeation are associated with a tendency of the oxidized lipid tails to bend towards the water interface. Our results suggest that the mechanism of cell membrane damage due to oxidized lipids may involve an increase in membrane permeability.

 J. Wong-ekkabut, None; L. Monticelli, None; Z. Xu, None; S. Baoukina, None; W. Triampo, None; I.M. Tang, None; P. Tieleman, None.