title: On the solvation structure of dimethylsulfoxide/water around the phosphatidylcholine head group in solution.
abstract: The solution structure of the phosphocholine (PC) head group in 1,2-dipropionyl-sn-glycero-3-phosphocholine (C(3)-PC) in 30 mol. % dimethylsulfoxide (DMSO)-water solutions has been determined by using neutron diffraction enhanced with isotopic substitution in combination with computer simulation techniques. By investigating the atomic scale hydration structure around the PC head group, a unique description of the displacement of water molecules by DMSO molecules is detailed around various locations of the head group. Specifically, DMSO molecules were found to be the most prevalent around the onium portion of the head group, with the dipoles of the DMSO molecules being aligned where the negatively charged oxygen can interact strongly with the positively charged lipid group. The phosphate group is also partially dehydrated by the presence of the DMSO molecules. However, around this group the bulkier positive end of the DMSO dipole is interacting with negatively charged groups of the lipid head group, the DMSO layer shows no obvious ordering as it cannot form hydrogen bonds with the oxygen atoms in the PO(4) group such as water molecules can. Interestingly, DMSO-water contacts have also increased in the presence of the lipid molecule relative to DMSO-water contacts observed in pure DMSO/water solutions at similar concentrations.
authors.affiliation: Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
authors.forename: Aleksandra P
authors.initials: AP
authors.lastname: Dabkowska
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Foglia
authors.forename: M Jayne
authors.initials: MJ
authors.lastname: Lawrence
authors.forename: Christian D
authors.initials: CD
authors.lastname: Lorenz
authors.forename: Sylvia E
authors.initials: SE
authors.lastname: McLain
mesh_terms: D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D010710:Phosphates / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry*; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D010710:Phosphates; D010713:Phosphatidylcholines; D012996:Solutions; D012997:Solvents; D014867:Water; D004121:Dimethyl Sulfoxide