Effects of ether vs. ester linkage on lipid bilayer structure and water permeability.
Date of Original Version
Abstract or Description
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.
Chemistry and physics of lipids, 160, 1, 33-44.