Interaction of rhodopsin with two unsaturated phosphatidylcholines: a deuterium nuclear magnetic resonance study.
Interaction of rhodopsin with two unsaturated phosphatidylcholines: a deuterium nuclear magnetic resonance study.
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视紫红质与两种不饱和磷脂酰胆碱的相互作用：氘核磁共振研究。
DOI：
10.1021/bi00525a021
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发表时间：
1981
期刊：
影响因子：
2.9
通讯作者：
Paddy,MR
中科院分区：
文献类型：
--
作者：
Deese,AJ;Dratz,EA;Dahlquist,FW;Paddy,MR
放大图片作者：Edward A. Dratz，F. W. Dahlquist，and Michael R. Paddy* 摘要：不含天然脂质的视紫红质用两种不饱和和特异性氘代磷脂酰胆碱重构：最低限度不饱和的1-（16，16，16-三氘棕榈酰）-2-棕榈油酰-N-甘油-3-磷酸胆碱[（CD3-16：0）（16：1）PC]和天然视杆细胞外节（ROS）膜中典型的高度不饱和磷脂酰胆碱，1-（16，16，16-三氘棕榈酰基）-2-二十二碳六烯酰基-γ-甘油基-3-磷酸胆碱[（CD 3 -16：0）（22：6）PC]。氘磁共振（2 H NMR）光谱的这些膜和分散体的脂质单独获得在23.0 MBz通过使用四极回波技术。在蛋白质存在下，表观四极分裂稍小，光谱特征有所加宽。这些光谱的矩分析表明，在流体相中，视紫红质在接近生理浓度（1：1 w/w）的存在下不改变任何脂质的平均取向顺序。视紫红质确实影响双层的结构，然而，通过引起平均值附近的取向序参数的分布的扩展的增加。在没有视紫红质的情况下，观察到两种脂质的相行为中的几个有趣的差异。（CD 3 -16：0）（16：1）PC和（CD 3 -16：0）（22：6）PC的取向顺序在相变区域中明显不同，尽管这两种脂质具有惊人相似的相变温度。22：含6的脂质在胰蛋白酶转变中表现出相对大的滞后（8-9 ℃），而对于（CD 3 -16：0）（16：1）PC没有观察到滞后。此外，（CD 3 -16：0）（22：6）PC的相变发生在比（CD 3 -16：0）（16：1）PC小得多的温度范围内。相变的滞后性和尖锐性都表明22：6脂质比16：1脂质具有更高程度的协同性。视紫红质的存在消除了（CD 3 -16：0）-（22：6）PC的这种滞后和急剧相变，并产生了与对（CD 3 -16：0）（16：1）-PC/视紫红质重构膜观察到的那些类似的平均取向顺序值，其与单独的16：1脂质相比没有变化。测量了含和不含视紫红质的脂质的自旋-晶格（7，）和四极回波衰减（7，）弛豫时间随温度的变化。对于所有样品，72 e对凝胶到液晶的相变非常敏感，而7 t相对不敏感。在液相中，视紫红质使两种脂质的δ t降低大约相同的量（约2倍），而在用22：6脂质重构的膜中产生比用16：1脂质制备的膜大2倍的δ t降低。这意味着，视紫红质差异改变两种脂质的低频重定向运动。总的来说，这些结果与我们以前对天然ROS膜和ROS脂质的13 C和31 P NMR研究一致：视紫红质不产生长寿命的高度有序的脂质群体。脊椎动物视网膜视杆细胞外段（ROS）1盘膜是视觉兴奋的部位。在这些膜中，发色蛋白视紫红质包含至少95%的整合膜蛋白（Krebs & Kuhn，1977）。视紫红质深深嵌入（ROS）盘膜双层中（Dratz et al. 1979），并且多肽链跨越膜（Fung & Hubbell，1978; Nemes等人，1980年）。ROS膜磷脂中的脂肪酸明显是多不饱和的;在牛ROS中，约50%的脂肪酸是不饱和的。
Alan J. Deese, Edward A. Dratz, F. W. Dahlquist, and Michael R. Paddy* abstract: Rhodopsin, prepared free of native lipid, was re-constituted with two unsaturated and specifically deuterated phosphatidylcholines: the minimally unsaturated 1-(16, 16, 16-trideuteriopalmitoyl)-2-palmitoleoyl-jvt-glycero-3-phosphocholine [(CD3-16: 0)(16: 1) PC] and a highly unsatu-rated phosphatidylcholine typical of that found in native rod outer segment (ROS) membranes, 1-(16, 16, 16-trideuteriopalmitoyl)-2-docosahexaenoyl-jn-glycero-3-phosphocholine [(CD3-16: 0)(22: 6) PC]. Deuterium magnetic resonance(2H NMR) spectra of these membranes and dispersions of the lipids alone were obtained at 23.0 MBz by using the quad-rupolar echo technique. The apparent quadrupolar splittings are slightly less and the spectral features are somewhat broadened in the presence of the protein. Moment analyses of these spectra show that in the fluid phase the presence of rhodopsin at near physiological concentrations (1: 1 w/w) does not change the average orientational order of either lipid. Rhodopsin does affect the structure of the bilayer, however, by causing an increase in the spread of the distribution of orientational order parameters about the average. Several interesting differences are observed in the phase behavior of the two lipids in the absence of rhodopsin. The orientational order of (CD3-16: 0)(16: 1) PC and (CD3-16: 0)(22: 6) PC is markedly different in the phase transition region, even though these two lipids have surprisingly similar phase transition temperatures. The 22: 6-containing lipid exhibits a relatively large hysteresis (8-9 C) in itsphase transition, while no hysteresis is observed for (CD3-16: 0)(16: 1) PC. Further, the phase transition for (CD3-16: 0)(22: 6) PC occurs over a much smaller temperature range than thatfor (CD3-16: 0)(16: 1) PC. Both the hysteresis andsharpness of the phase transition suggest a higher degree of cooperativity in the 22: 6 lipid than in the 16: 1 lipid. The presence of rhodopsin eliminates this hysteresis and sharp phase transition of the (CD3-16: 0)-(22: 6) PC and produces values of the average orientational order similar to those observed for the (CD3-16: 0)(16: 1)-PC/rhodopsin reconstituted membranes, which are unchanged from the 16: 1 lipid alone. Spin-lattice (7,) and quadrupolar echo decay (7^) relaxation times were measured as a function of temperature for the lipids with and without rhodopsin. For all of thesamples, 72e is very sensitive to the gel to liquid crystal phase transition, while 7t is relatively insensitive. In the fluid phase, rhodopsin decreases 7t by approximately the same amount (about2-fold) for both lipids while producing a 2-fold greater decrease in 7^ in the membranes reconstituted with the 22: 6 lipid as opposed to the membranes prepared with the 16: 1 lipid. This implies that rhodopsin differentially alters low-frequency reorientational motions of the two lipids. Overall, these results are consistent with our previous, 13C, and 31P NMR studies of native ROS membranes and ROS lipids: rhodopsin does not produce a long-lived, highly ordered population of lipids. e vertebrate retinal rod outer segment (ROS) 1 disk membrane is the site of visual excitation. In these membranes, the chromophoric protein rhodopsin comprises at least 95% of the integral membrane protein (Krebs & Kuhn, 1977).Rhodopsin is deeply embedded in the (ROS) disk membrane bilayer (Dratz et al., 1979), and the polypeptide chain spans the membrane (Fung & Hubbell, 1978; Nemes et al., 1980). The fatty acids in the ROS membrane phospholipids are strikingly polyunsaturated; in cattle ROS, about 50% of the