Johnson S J, Bayerl T M, McDermott D C, Adam G W, Rennie A R, Thomas R K, Sackmann E
Technische Universität München, Federal Republic of Germany.
Biophys J. 1991 Feb;59(2):289-94. doi: 10.1016/S0006-3495(91)82222-6.
Using specular reflection of neutrons, we investigate for the first time the structure of a single dimyristoylphosphatidylcholine bilayer adsorbed to a planar quartz surface in an aqueous environment. We demonstrate that the bilayer is strongly adsorbed to the quartz surface and is stable to phase state changes as well as exchange of the bulk aqueous phase. Our results show that the main phase transition is between the L alpha phase and the metastable L beta'* phase, with formation of the P beta' ripple phase prevented by lateral stress on the adsorbed bilayer. By performing contrast variation experiments, we are able to elucidate substantial detail in the interfacial structure. We measure a bilayer thickness of 43.0 +/- 1.5 A in the L alpha phase (T = 31 degrees C) and 46.0 +/- 1.5 A in the L beta'* phase (T = 20 degrees C). The polar head group is 8.0 +/- 1.5 A thick in the L alpha phase. The water layer between the quartz and bilayer is 30 +/- 10 A for the lipid in both the L alpha and L'* phase. Our results agree well with those previously reported from experiments using lipid vesicles and monolayers, thus establishing the feasibility of our experimental methods.
利用中子的镜面反射，我们首次研究了在水环境中吸附于平面石英表面的单个二肉豆蔻酰磷脂酰胆碱双层膜的结构。我们证明该双层膜强烈吸附于石英表面，并且对相态变化以及本体水相的交换具有稳定性。我们的结果表明，主要相变发生在Lα相和亚稳Lβ'*相之间，由于吸附双层膜上的侧向应力，阻止了Pβ'波纹相的形成。通过进行对比变化实验，我们能够阐明界面结构的大量细节。我们测得Lα相（T = 31℃）时双层膜厚度为43.0±1.5 Å，Lβ'*相（T = 20℃）时为46.0±1.5 Å。在Lα相中，极性头部基团厚度为8.0±1.5 Å。对于处于Lα相和L'*相的脂质，石英与双层膜之间的水层厚度为30±10 Å。我们的结果与先前使用脂质囊泡和单分子层的实验报道结果非常吻合，从而证实了我们实验方法的可行性。
