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Effects of ether vs. ester linkage on lipid bilayer structure and water permeability |
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| Authors: | S. Deren Guler Jianjun Pan Mark L. Zeidel Stephanie Tristram-Nagle |
| Affiliation: | a Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA b Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA c Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Cambridge, MA 02139, USA |
| Abstract: | The structure and water permeability of bilayers composed of the ether-linked lipid, dihexadecylphosphatidylcholine (DHPC), were studied and compared with the ester-linked lipid, dipalmitoylphosphaditdylcholine (DPPC). Wide angle X-ray scattering on oriented bilayers in the fluid phase indicate that the area per lipid A is slightly larger for DHPC than for DPPC. Low angle X-ray scattering yields A = 65.1 Å2 for DHPC at 48 °C. LAXS data provide the bending modulus, KC = 4.2 × 10−13 erg, and the Hamaker parameter H = 7.2 × 10−14 erg for the van der Waals attractive interaction between neighboring bilayers. For the low temperature phases with ordered hydrocarbon chains, we confirm the transition from a tilted Lβ′ gel phase to an untilted, interdigitated LβI phase as the sample hydrates at 20 °C. Our measurement of water permeability, Pf = 0.022 cm/s at 48 °C for fluid phase DHPC is slightly smaller than that of DPPC (Pf = 0.027 cm/s) at 50 °C, consistent with our triple slab theory of permeability. |
| Keywords: | Ether lipid X-ray Structure Water permeability Lipid bilayers |
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