title: Specific volumes of unsaturated phosphatidylcholines in the liquid crystalline lamellar phase.
abstract: The specific volumes of seven 1,2-diacyl-sn-glycero-3-phosphocholines with symmetric, unbranched acyl chains containing one, four, or six cis double bonds per chain, or with a saturated sn-1 chain and one, four, or six cis double bonds in the sn-2 chain were determined by the neutral buoyancy method. Experiments were conducted in the liquid crystalline lamellar phase over the temperature range from 5 to 35 degrees C. It is demonstrated that the molecular volume of phosphatidylcholines can be well approximated as the sum of a constant volume of the polar lipid head region and the temperature-dependent volumes of hydrocarbon chain CH2, CH, and terminal CH3 groups. A linear dependence of chain segment volumes on temperature was observed. A self-consistent set of partially temperature-dependent volumes is obtained that allows prediction of phosphatidylcholine molecular volumes within very tight error margins.
authors.affiliation: Structural Biology Institute, IBI-2, Research Center Jülich, Düsseldorf, Germany. b.koenig@fz-juelich.de
authors.forename: Bernd W
authors.initials: BW
authors.lastname: Koenig
authors.forename: Klaus
authors.initials: K
authors.lastname: Gawrisch
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D013696:Temperature
chemical_list: D005231:Fatty Acids, Unsaturated; D008563:Membrane Lipids; D010713:Phosphatidylcholines