Vié V, Van Mau N, Chaloin L, Lesniewska E, Le Grimellec C, Heitz F
CBS, INSERM-U414, IURC, 34093 Montpellier Cedex 5, 21011 Dijon Cedex, France.
Biophys J. 2000 Feb;78(2):846-56. doi: 10.1016/S0006-3495(00)76642-2.
To improve the understanding of the membrane uptake of an amphipathic and positively charged vector peptide, we studied the interactions of this peptide with different phospholipids, the nature of whose polar headgroups and physical states were varied. Three lipids were considered: dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG), and dioleoylphosphatidylglycerol (DOPG). The approach was carried out by three complementary methods: compression isotherms of monolayers and atomic force microscopy observations associated with Fourier transform infrared investigations. From analysis of the compression isotherms, it was concluded that the peptide interacts with all lipids and with an expansion of the mean molecular area, implying that both components form nonideal mixtures. The expansion was larger in the case of DOPG than for DPPC and DPPG because of an alpha to beta conformational transition with an increase in the peptide molar fraction. Atomic force microscopy observations showed that the presence of small amounts of peptide led to the appearance of bowl-like particles and that an increase in the peptide amounts generated the formation of filaments. In the case of DOPG, filaments were found at higher peptide molar fractions than already observed for DOPC because of the presence of negatively charged lipid headgroups.
为了增进对一种两亲性带正电荷载体肽膜摄取的理解，我们研究了该肽与不同磷脂的相互作用，这些磷脂的极性头部基团性质和物理状态各不相同。我们考虑了三种脂质：二棕榈酰磷脂酰胆碱（DPPC）、二棕榈酰磷脂酰甘油（DPPG）和二油酰磷脂酰甘油（DOPG）。该研究采用了三种互补方法：单层压缩等温线以及与傅里叶变换红外光谱研究相关的原子力显微镜观察。通过对压缩等温线的分析得出结论，该肽与所有脂质相互作用，且平均分子面积增大，这意味着两种成分形成了非理想混合物。由于随着肽摩尔分数增加发生α到β的构象转变，DOPG情况下的分子面积增大比DPPC和DPPG更为显著。原子力显微镜观察表明，少量肽的存在导致碗状颗粒出现，肽量增加则产生细丝形成。在DOPG情况下，由于存在带负电荷的脂质头部基团，在比DOPC已观察到的更高肽摩尔分数下发现了细丝。
