Sanders C R, Schaff J E, Prestegard J H
Department of Chemistry, Yale University, New Haven, Connecticut 06511.
Biophys J. 1993 Apr;64(4):1069-80. doi: 10.1016/S0006-3495(93)81473-5.
A number of aromatic-containing additives which can influence the orientation of fragments of lipid bilayer membranes by a magnetic field have been investigated. Two properties of these additives prove important: (1) sufficient detergency to facilitate reorganization of bilayer components and (2), sufficient anisotropy in magnetic susceptibility the preferred direction of fragment orientation. Triton X-100 is identified as effective in terms of facilitating magnetic field ordering of bilayer fragments but does not alter the preferred direction of orientation. A combination of the detergent CHAPSO (3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate) and the aromatic alcohol 1-naphthol facilitates both ordering and alters the preferred direction of bilayer orientation. As mixtures of dimyristoylphosphatidylcholine (DMPC) and CHAPSO, which orient with bilayer normals perpendicular to the magnetic field, were titrated with 1-naphthol, the assemblies underwent transitions, first to random orientation, and then to an orientation with bilayer normals parallel to the field. Based on temperature-induced phase transitions and the extent of motional averaging of the 31P shielding tensor of the DMPC headgroup, the DMPC in these oriented samples appears to maintain a bilayer morphology during transitions. The insight provided in this study regarding factors which influence fragment stability and orientation lays the groundwork for the design of improved field-oriented media for spectroscopic investigation of membrane components.
已经研究了许多能够通过磁场影响脂质双分子层膜片段取向的含芳香族添加剂。这些添加剂的两个特性被证明很重要：（1）具有足够的去污能力以促进双分子层成分的重组；（2）磁化率具有足够的各向异性，即片段取向的优选方向。就促进双分子层片段的磁场有序排列而言，Triton X-100被认为是有效的，但它不会改变优选的取向方向。去污剂CHAPSO（3-[(3-胆酰胺丙基)-二甲基铵]-1-丙烷磺酸盐）和芳香醇1-萘酚的组合既促进了有序排列，又改变了双分子层取向的优选方向。当用1-萘酚滴定以双分子层法线垂直于磁场取向的二肉豆蔻酰磷脂酰胆碱（DMPC）和CHAPSO的混合物时，组装体经历了转变，首先转变为随机取向，然后转变为双分子层法线平行于磁场的取向。基于温度诱导的相变以及DMPC头部基团的31P屏蔽张量的运动平均程度，这些取向样品中的DMPC在转变过程中似乎保持双分子层形态。本研究中提供的关于影响片段稳定性和取向的因素的见解为设计用于膜成分光谱研究的改进的场取向介质奠定了基础。
