Seu Kalani J, Cambrea Lee R, Everly R Michael, Hovis Jennifer S
Department of Chemistry, Purdue University, West Lafayette, Indiana, USA.
Biophys J. 2006 Nov 15;91(10):3727-35. doi: 10.1529/biophysj.106.084590. Epub 2006 Sep 1.
Membrane fluidity plays an important role in cell function and may, in many instances, be adjusted to facilitate specific cellular processes. To understand better the effect that lipid chemistry has on membrane fluidity the inclusion of three different lipids into egg phosphatidylcholine (eggPC) bilayers has been examined; the three lipids are egg phosphatidylethanolamine ((eggPE) made by transphosphatidylation of eggPC in the presence of ethanolamine), lyso-phosphatidylcholine (LPC), and lyso-phosphatidylethanolamine (LPE). The fluidity of the membranes was determined using fluorescence recovery after photobleaching and the intermolecular interactions were examined using attenuated total reflection Fourier transform infrared spectroscopy. It was observed that both headgroup and tail chemistry can significantly modulate lipid diffusion. Specifically, the inclusion of LPC and eggPE significantly altered the lipid diffusion, increased and decreased, respectively, whereas the inclusion of LPE had an intermediate effect, a slight decrease in diffusion. Strong evidence for the formation of hydrogen-bonds between the phosphate group and the amine group in eggPE and LPE was observed with infrared spectroscopy. The biological implications of these results are discussed.
膜流动性在细胞功能中起着重要作用，并且在许多情况下，可以进行调节以促进特定的细胞过程。为了更好地理解脂质化学对膜流动性的影响，研究人员将三种不同的脂质加入到卵磷脂酰胆碱（eggPC）双层膜中进行了研究；这三种脂质分别是：卵磷脂酰乙醇胺（eggPE，通过在乙醇胺存在下对eggPC进行转磷脂酰基化反应制得）、溶血卵磷脂酰胆碱（LPC）和溶血卵磷脂酰乙醇胺（LPE）。使用光漂白后的荧光恢复技术测定膜的流动性，并使用衰减全反射傅里叶变换红外光谱法研究分子间相互作用。研究发现，头部基团和尾部化学结构均可显著调节脂质扩散。具体而言，加入LPC和eggPE分别显著改变了脂质扩散，使其增加和减少，而加入LPE则产生中等程度的影响，使扩散略有下降。红外光谱观察到了eggPE和LPE中磷酸基团与胺基团之间形成氢键的有力证据。文中讨论了这些结果的生物学意义。
