Effects of ether vs. ester linkage on lipid bilayer structure and water permeability.
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=65.1A(2) for DHPC at 48 degrees C. LAXS data provide the bending modulus, K(C)=4.2x10(-13)erg, and the Hamaker parameter H=7.2x10(-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 L(beta') gel phase to an untilted, interdigitated L(beta)I phase as the sample hydrates at 20 degrees C. Our measurement of water permeability, P(f)=0.022cm/s at 48 degrees C for fluid phase DHPC is slightly smaller than that of DPPC (P(f)=0.027cm/s) at 50 degrees C, consistent with our triple slab theory of permeability.
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
S Deren
SD
Guler
D Dipon
DD
Ghosh
Jianjun
J
Pan
John C
JC
Mathai
Mark L
ML
Zeidel
John F
JF
Nagle
Stephanie
S
Tristram-Nagle
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000465:Algorithms; D004952:Esters / Q000737:chemistry; D004987:Ethers / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D010539:Permeability; D012542:Scattering, Radiation; D014867:Water / Q000737:chemistry*
D004952:Esters; D004987:Ethers; D008051:Lipid Bilayers; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine