Hirsh D J, Lazaro N, Wright L R, Boggs J M, McIntosh T J, Schaefer J, Blazyk J
Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
Biophys J. 1998 Oct;75(4):1858-68. doi: 10.1016/S0006-3495(98)77626-X.
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.
使用二乙氨基三氟化硫由16-羟基棕榈酸合成了16-氟棕榈酸。然后，这种单氟化脂肪酸被用于制备1-棕榈酰-2-[16-氟棕榈酰]-磷脂酰胆碱（F-DPPC），作为二棕榈酰磷脂酰胆碱（DPPC）的氟化类似物。令人惊讶的是，我们发现通过差示扫描量热法和红外光谱法判断，F-DPPC的相变温度（Tm）出现在50摄氏度左右，比其非氟化对应物DPPC高出约10摄氏度。F-DPPC中不存在DPPC所观察到的预转变。REDOR、旋转回波双共振和传统固态核磁共振实验的结合表明，F-DPPC在凝胶相中形成了完全交错的双层结构。电子顺磁共振实验表明，在Tm以下，F-DPPC的烃链比DPPC的烃链在运动上受到更多限制。X射线散射实验证实，凝胶相F-DPPC的厚度和堆积与庚三醇诱导的交错DPPC相似。F-DPPC是第一种含有等长的sn-1和sn-2酯键连接脂肪酰链的磷酸甘油酯，在没有醇类等诱导剂的情况下，能在凝胶态自发形成交错双层结构。
