High-pressure 31P NMR study of dipalmitoylphosphatidylcholine bilayers.
High-pressure 31P NMR study of dipalmitoylphosphatidylcholine bilayers.
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二棕榈酰磷脂酰胆碱双层的高压 31P NMR 研究。
DOI：
10.1021/bi00143a004
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发表时间：
1992
期刊：
影响因子：
2.9
通讯作者：
Jonas,J
中科院分区：
文献类型：
--
作者：
Peng,X;Jonas,J
Department of Chemistry，School of Chemical Sciences，University of Illinois，Urbana，Illinois 61801 1992年2月4日接收; 1992年4月22日接收的修订版手册摘要：首次采用高压~（31）P NMR研究了压力对磷酸胆碱头基结构和动力学的影响，2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）多层水性分散体和含有带正电荷形式的局部麻醉剂丁卡因（TTC）的DPPC双层。测量了纯DPPC和DPPC/TTC双层膜的~（31）P化学位移各向异性和~（31）P自旋-晶格弛豫时间（7 h）随压力的变化。该压力范围使我们能够探索DPPC从液晶（LC）相到各种凝胶相（例如凝胶I（Pi）、凝胶II（Li）、凝胶III、凝胶IV、凝胶X）和交叉指型凝胶（Gi）相的富相行为。对于纯DPPC双分子层，压力对同一相中的磷脂头基具有有序化效应，并诱导在凝胶I（P/）和凝胶II（L/）相之间形成叉指型Gi凝胶相。~（31）P自旋-晶格弛豫时间测量表明，主要相变（LC到凝胶I）伴随着快、慢关联时间区之间的转变。轴对称的~（31）P核磁共振谱线在~ 3 kbar的压力下观察到，但在更高的压力下（3.1- 5.1kbar），谱线变成了轴对称的刚性点阵谱线。正如预期的那样，添加带正电荷形式的TTC增加了31 P化学位移各向异性的绝对值，||，并导致头基的构象发生变化，从通常平行于膜表面的方向转向双层法线。TTC的加入也提高了主相转变的临界压力，并诱导直接从LC相形成叉指型Gi凝胶相。有趣的是，31 P的表达式，谢勒和Seelig（1989）提出的测定表面电荷对磷脂双分子膜极性头基的影响的方法，在高压下适用于LC相，在压力超过3.5kbar时也适用于凝胶相。实验技术，包括IR和拉曼光谱（Wong，1987 a，B），荧光光谱（Chong，1988; Chong和Weber，1983），X-射线衍射（Stamatoff等，1978）、中子散射（Braganza和Worcester，1986 a，B; Winter和Pilgrim，1989; Winter等人，1991）、NMR 1（Jonas等人，1988年; Drivel等人，1991 a，B）和光透射（Prasad等人，1987年）。在膜的研究中，恒温下的压力变化可以使我们识别纯体积效应，此外，它还可以使我们连续地改变所研究体系中的分子间相互作用。相比之下，温度变化导致同时的热效应和体积效应，这是非常难以分开的。通过对膜系统施加高压，不仅可以观察到体积效应，而且可以产生新的压力诱导相（Wong等人，1988年）。已经生成了几种磷脂系统的温度-压力相图（Braganza和Worcester，1986 a，B; Prasad等人，1987; Wong等人，1988年）。在我们的实验室中，我们已经开始对模型磷脂膜进行系统的高压NMR研究（Jonas等人，1988，1990; Drivel等人，1991 a，B）。与本研究特别相关的是两个......
Department of Chemistry, School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801 Received February 4, 1992; Revised Manuscript Received April 22, 1992 abstract: High-pressure 31P NMR was used for the first time to investigate the effects of pressure on the structure and dynamics of the phosphocholine headgroup in pure 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) multilamellar aqueous dispersions and in DPPC bilayers containing the positively charged form of the local anesthetic tetracaine (TTC). The 31P chemical shift anisotropies,, and the 31P spin-lattice relaxation times, 7h were measured as a function of pressure from 1 bar to 5 kbar at 50 C for both pure DPPC and DPPC/TTC bilayers. This pressure range permitted us to explore the rich phase behavior of DPPC from the liquid-crystalline (LC) phase through various gel phases such as gel I (P/), gel II (L/), gel III, gel IV, gel X, and the interdigitated, Gi, gel phase. For pure DPPC bilayers, pressure had an ordering effect on the phospholipid headgroup within the same phase and induced an interdigitated Gi gel phase which was formed between the gel I (P/) and gel II (L/) phases. The 31P spin-lattice relaxation time measurements showed that the main phase transition (LC to gel I) was ac-companied by the transition between the fast and slow correlation time regimes. Axially symmetric 31P NMR lineshapes were observed at pressures up to~ 3 kbar but changed to characteristic axially asymmetric rigid lattice lineshapes athigher pressures (3.1-5.1 kbar). As expected, the addition of the positively charged form of TTC increased the absolute value of the 31P chemical shift anisotropy,||, and brought about a change in the conformation of the headgroup which swung toward the bilayer normal, from its usual orientation parallel to the membrane surface. The addition of TTC also raised the critical pressure of the main phase transition and induced the formation of an interdigitated Gi gel phase directly from the LC phase. Interestingly the expressions for 31P,, introduced by Scherer and Seelig (1989) to determine the effect of electric surface charge on the polar headgroup of phospholipid bilayers were found applicable for the LC phase at high pressures and also for the gel phases at pressures in excess of 3.5 kbar.There has been a growing interest in pressure as an exper-imental variable in studies of membranes by a variety of ex-perimental techniques, including IR and Raman spectroscopy (Wong, 1987a, b), fluorescence spectroscopy (Chong, 1988; Chong & Weber, 1983), X-ray diffraction (Stamatoff et al., 1978), neutron scattering (Braganza & Worcester, 1986a, b; Winter & Pilgrim, 1989; Winter et al., 1991), NMR1 (Jonas et al., 1988; Driscoll et al., 1991a, b), and light transmission (Prasad et al., 1987). Pressure variation at constant temperature in studies of membranes allows theidentification of pure volume effects, and in addition, it also allows us to change continuously the intermolecular interaction in the system studied. In contrast, temperature changes result in simulta-neous thermal and volume effects which are very difficult to separate. Byapplying high pressure to membrane systems, one can not only observe volume effects but produce new pressure-induced phases (Wong et al., 1988). Temperature-pressure phase diagrams have been generated for several phospholipid systems (Braganza & Worcester, 1986a, b; Prasad et al., 1987; Wong et al., 1988). In our laboratory, we have initiated systematic high-pressure NMR studies on model phospholipid membranes (Jonas et al., 1988, 1990; Driscoll et al., 1991a, b). Of particular relevance to the present study are two of …