Molecular dynamics simulations of mixed acidic/zwitterionic phospholipid bilayers.
Anionic lipids are key components in the cell membranes. Many cell-regulatory and signaling mechanisms depend upon a complicated interplay between them and membrane-bound proteins. Phospholipid bilayers are commonly used as model systems in experimental or theoretical studies to gain insight into the structure and dynamics of biological membranes. We report here 200-ns-long MD simulations of pure (DMPC and DMPG) and mixed equimolar (DMPC/DMPG, DMPC/DMPS, and DMPC/DMPA) bilayers that each contain 256 lipids. The intra- and intermolecular interaction patterns in pure and mixed bilayers are analyzed and compared. The effect of monovalent ions (Na+) on the formation of salt-bridges is investigated. In particular, the number of Na(+)-mediated clusters in the presence of DMPS is higher than with DMPG and DMPA. We observe a preferential clustering of DMPS (and to some extent DMPA) lipids together rather than with DMPC molecules, which can explain the phase separation observed experimentally for DMPC/DMPS and DMPC/DMPA bilayers.
Broemstrup
Torben
T
Computational Biology Unit, Bergen Center for Computational Science, University of Bergen, Bergen, Norway.
Reuter
Nathalie
N
D000143:Acids / Q000737:chemistry*; D055592:Biophysical Phenomena; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D006860:Hydrogen Bonding; D007477:Ions; D008051:Lipid Bilayers / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010715:Phosphatidylglycerols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D012964:Sodium / Q000378:metabolism
D000143:Acids; D007477:Ions; D008051:Lipid Bilayers; D010715:Phosphatidylglycerols; D010743:Phospholipids; D012964:Sodium; C002773:dimyristoylphosphatidylglycerol; D004134:Dimyristoylphosphatidylcholine