Achilles Anja, Bärenwald Ruth, Lechner Bob-Dan, Werner Stefan, Ebert Helgard, Tschierske Carsten, Blume Alfred, Bacia Kirsten, Saalwächter Kay
Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany.
Langmuir. 2016 Jan 26;32(3):673-82. doi: 10.1021/acs.langmuir.5b03712. Epub 2016 Jan 15.
A novel class of rigid-rod bolapolyphilic molecules with three philicities (rigid aromatic core, mobile aliphatic side chains, polar end groups) has recently been demonstrated to incorporate into and span lipid membranes, and to exhibit a rich variety of self-organization modes, including macroscopically ordered snowflake structures with 6-fold symmetry. In order to support a structural model and to better understand the self-organization on a molecular scale, we here report on proton and carbon-13 high-resolution magic-angle spinning solid-state NMR investigations of two different bolapolyphiles (BPs) in model membranes of two different phospholipids (DPPC, DOPC). We elucidate the changes in molecular dynamics associated with three new phase transitions detected by calorimetry in composite membranes of different composition, namely, a change in π-π-packing, the melting of lipid tails associated with the superstructure, and the dissolution and onset of free rotation of the BPs. We derive dynamic order parameters associated with different H-H and C-H bond directions of the BPs, demonstrating that the aromatic cores are well packed below the final phase transition, showing only 180° flips of the phenyl ring, and that they perform free rotations with additional oscillations of the long axis when dissolved in the fluid membrane. Our data suggests that BPs not only form ordered superstructures, but also rather homogeneously dispersed π-packed filaments within the lipid gel phase, thus reducing the corrugation of large vesicles.
最近已证实，一类新型的具有三种亲性（刚性芳香核、可移动脂肪族侧链、极性端基）的刚性棒状双亲性分子能够掺入并跨越脂质膜，并呈现出丰富多样的自组装模式，包括具有六重对称性的宏观有序雪花结构。为了支持一种结构模型并更好地理解分子尺度上的自组装，我们在此报告了对两种不同磷脂（二棕榈酰磷脂酰胆碱，二油酰磷脂酰胆碱）的模型膜中两种不同双亲性分子（BPs）进行的质子和碳 - 13 高分辨率魔角旋转固态核磁共振研究。我们阐明了在不同组成的复合膜中通过量热法检测到的三个新相变所伴随的分子动力学变化，即 π - π堆积的变化、与超结构相关的脂质尾部的熔化，以及 BPs 的溶解和自由旋转的开始。我们推导了与 BPs 不同 H - H 和 C - H 键方向相关的动态序参数，表明芳香核在最终相变以下堆积良好，仅显示苯环的 180°翻转，并且当溶解在流体膜中时，它们会进行自由旋转并伴有长轴的额外振荡。我们的数据表明，BPs 不仅形成有序的超结构，而且在脂质凝胶相中还相当均匀地分散着 π - 堆积的细丝，从而减少了大囊泡的波纹。
