Molecular Structures of Fluid Phase Phosphatidylglycerol Bilayers as Determined by Small Angle Neutron and X-ray Scattering

Journal Article · Sat Dec 31 23:00:00 EST 2011 · Biochimica et Biophysica Acta (BBA) - Biomembranes

DOI:https://doi.org/10.1016/j.bbamem.2012.05.007· OSTI ID:1042897

Pan, Jianjun ^[1]; Heberle, Frederick A ^[1]; Tristram-Nagle, Dr. Stephanie ^[2]; Michelle, Szymanski ^[3]; Mary, Koepfinger ^[3]; Katsaras, John ^[1]; Kucerka, Norbert ^[4]

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1. ORNL
2. Carnegie Mellon University
3. Rutgers University
4. Canadian Neutron Beam Centre and Comelius University (Slovakia)

We have determined the molecular structures of commonly used phosphatidylglycerols (PGs) in the commonly accepted biologically relevant fluid phase. This was done by simultaneously analyzing small-angle neutron and X-ray scattering data, with the constraint of a measured volume per lipid. We report the temperature dependence of bilayer parameters obtained using the one dimensional scattering density profile model derived from molecular dynamics simulations, including the area per lipid, the overall bilayer thickness, as well as other intrabilayer parameters (e.g., hydrocarbon thickness). Lipid areas are found to be larger than their phosphatidylcholine (PC) counterparts, a result likely due to repulsive electrostatic interactions taking place between the charged PG headgroups even in the presence of Na+ counterions. In general, PG and PC bilayers show a similar response to changes in temperature and chain length, but differ in their response to chain unsaturation. For example, compared to their PC counterparts, the inclusion of a double bond in PG lipids results in a smaller incremental change in lipid area and bilayer thickness. However, the extrapolated lipid area of saturated PG lipids at infinite chain length is found to be similar to that of PCs, an indication of the glycerol-carbonyl backbone's pivotal role in influencing the lipid-water interface.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
• Sponsoring Organization: ORNL LDRD Director's R&D
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1042897
• Journal Information: Biochimica et Biophysica Acta (BBA) - Biomembranes, Journal Name: Biochimica et Biophysica Acta (BBA) - Biomembranes Journal Issue: 9 Vol. 1818; ISSN 0005-2736
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BIOLOGICAL MATERIALS
DOUBLE BONDS
ELECTROSTATICS
FLUIDS
HYDROCARBONS
INTERFACES
LAYERS
LECITHINS
LIPIDS
MOLECULAR DYNAMICS METHOD
MOLECULAR STRUCTURE
NEUTRON DIFFRACTION
SMALL ANGLE SCATTERING
TEMPERATURE DEPENDENCE
THICKNESS
WATER
X-RAY DIFFRACTION