title: Properties of ternary phospholipid/dimethyl sulfoxide/water systems at low temperatures.
abstract: X-ray diffraction, neutron diffraction and differential scanning calorimetry were used to investigate phase transitions in the ternary system phospholipid/dimethyl sulfoxide (DMSO)/water under cooling for three homologous phospholipids: dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), and distearoylphosphatidylcholine (DSPC). Below the temperature of ice formation from -40 to -113 degrees C, a new lamellar phase of DPPC and DSPC was found at and above a DMSO molar fraction of X(DMSO) = 0.05. Below X(DMSO) = 0.05 only a single dehydrated Lc-phase exists after ice formation. The new phase has an increased membrane repeat distance and coexists with a dehydrated Lc-phase. DPPC with a DMSO molar fraction of X(DMSO) = 0.07 shows a membrane repeat distance of the new phase of d = 6.61 +/- 0.03 nm. The value of d increases at the increase of X(DMSO). The new phase was not observed in the ternary system with DMPC. No correlation between the new phase and the glass transition of bound water in the intermembrane space was detected. The new phase was detected only in the systems with excess of water. The creation of the new phase demonstrates the specific DMSO interaction with hydrocarbon chains.
authors.affiliation: Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia. kiselev@nf.jinr.ru
authors.forename: M A
authors.initials: MA
authors.lastname: Kiselev
authors.forename: T
authors.initials: T
authors.lastname: Gutberlet
authors.forename: P
authors.initials: P
authors.lastname: Lesieur
authors.forename: T
authors.initials: T
authors.lastname: Hauss
authors.forename: M
authors.initials: M
authors.lastname: Ollivon
authors.forename: R H H
authors.initials: RH
authors.lastname: Neubert
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D003080:Cold Temperature; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D008567:Membranes, Artificial; D033363:Neutron Diffraction; D044367:Phase Transition; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010743:Phospholipids; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; C010942:1,2-distearoyllecithin; D004134:Dimyristoylphosphatidylcholine; D004121:Dimethyl Sulfoxide