title: Structure and dynamics of water at the interface with phospholipid bilayers.
abstract: We have performed two molecular-dynamics simulations to study the structural and dynamical properties of water at the interface with phospholipid bilayers. In one of the simulations the bilayer contained neutral phospholipid molecules, dioleoylphosphatidylcholine (DOPC); in the second simulation the bilayer contained charged lipid molecules, dioleoylphosphatidylserine (DOPS). From the density profile of water we observe that water next to the DOPS bilayer is more perturbed as compared to water near the DOPC bilayer. Using an energetic criterion for the determination of hydrogen bonding we find that water molecules create strong hydrogen bonds with the headgroups of the phospholipid molecules. Due to the presence of these bonds and also due to the confinement of water, the translational and orientational dynamics of water at the interface are slowed down. The degree of slowing down of the dynamics depends upon the location of water molecules near a lipid headgroup.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. bhide@email.unc.edu
authors.forename: Shreyas Y
authors.initials: SY
authors.lastname: Bhide
authors.forename: Max L
authors.initials: ML
authors.lastname: Berkowitz
mesh_terms: D002627:Chemistry, Physical / Q000379:methods*; D003198:Computer Simulation; D004583:Electrons; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015233:Models, Statistical; D010713:Phosphatidylcholines / Q000737:chemistry*; D010718:Phosphatidylserines / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D011336:Probability; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008055:Lipids; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D010743:Phospholipids; D014867:Water; C042511:1,2-dioleoylphosphatidylserine; C017251:1,2-oleoylphosphatidylcholine