A new monofluorinated phosphatidylcholine forms interdigitated bilayers.
16-Fluoropalmitic acid was synthesized from 16-hydroxypalmitic acid using diethylaminosulfur trifluoride. This monofluorinated fatty acid then was used to make 1-palmitoyl-2-[16-fluoropalmitoyl]-phosphatidylcholine (F-DPPC) as a fluorinated analog of dipalmitoylphosphatidylcholine (DPPC). Surprisingly, we found that the phase transition temperature (Tm) of F-DPPC occurs near 50 degrees C, approximately 10 degrees C higher than its nonfluorinated counterpart, DPPC, as judged by both differential scanning calorimetry and infrared spectroscopy. The pretransition observed for DPPC is absent in F-DPPC. A combination of REDOR, rotational-echo double-resonance, and conventional solid-state NMR experiments demonstrates that F-DPPC forms a fully interdigitated bilayer in the gel phase. Electron paramagnetic resonance experiments show that below Tm, the hydrocarbon chains of F-DPPC are more motionally restricted than those of DPPC. X-ray scattering experiments confirm that the thickness and packing of gel phase F-DPPC is similar to that of heptanetriol-induced interdigitated DPPC. F-DPPC is the first phosphoglyceride containing sn-1 and sn-2 ester-linked fatty acyl chains of equal length that spontaneously forms interdigitated bilayers in the gel state in the absence of inducing agents such as alcohols.
Hirsh
D J
DJ
Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
Lazaro
N
N
Wright
L R
LR
Boggs
J M
JM
McIntosh
T J
TJ
Schaefer
J
J
Blazyk
J
J
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000031:analogs & derivatives* / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004578:Electron Spin Resonance Spectroscopy; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010169:Palmitic Acids / Q000138:chemical synthesis; D010713:Phosphatidylcholines / Q000138:chemical synthesis / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014961:X-Ray Diffraction
C115319:1-palmitoyl-2-(16-fluoropalmitoyl)phosphatidylcholine; D008051:Lipid Bilayers; D010169:Palmitic Acids; D010713:Phosphatidylcholines; D015060:1,2-Dipalmitoylphosphatidylcholine; C031266:16-fluoropalmitic acid