STRUCTURE AND DYNAMIC PROPERTIES OF DIUNSATURATED ITOYL-2-LINOLEOYL-SN-GLYCERO-3-PHOSPHATIDYLCHOLINE LIPID BILAYER FROM MOLECULAR-DYNAMICS SIMULATION

Unsaturated fatty acid chains are known to be an essential structural part of biomembranes, but only monounsaturated chains have been includ ed in the molecular dynamics (MD) simulations of membrane systems. Her e we present a 1-ns MD simulation for a diunsaturated itoyl-2-linoleoy l-sn-glycero-3-phosphatidylcholine (PLPC; 16:0/18:2(Delta 9,12)) bilay er. The structural behavior of the phosphatidylcholine headgroup, the glycerol backbone, and the hydrating water were assessed and found to be consistent with the existing information about similar systems from both experimental and computational studies. Further analysis was foc used on the structure of the double bond region and the effects of the diunsaturation on the bilayer interior. The behavior of the diunsatur ated sn-2 chains is affected by the tilted beginning of the chain and the four main conformations of the double bond region. The double bond s of the sn-2 chains also influenced the characteristics of the satura ted chains in the sn-1 position. Furthermore, extreme conformations of the sn-2 chains existed that are likely to be related to the function al role of the double bonds. The results here point out the importance of polyunsaturation for the biological interpretations deduced from t he membrane MD simulations.