Electrostatic contributions to indole-lipid interactions
Electrostatic contributions to indole-lipid interactions
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DOI：
10.1021/jp0511000
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发表时间：
2005-07-07
影响因子：
3.3
通讯作者：
Gawrisch, K
中科院分区：
文献类型：
--
作者：
Gaede, HC;Yau, WM;Gawrisch, K
利用H-1和H-2核磁共振研究了吲哚与脂质相互作用中静电力的作用。吲哚环电流诱导的1-棕榈酰-2-油基-sn-甘油-3-磷胆碱、1,2-二油基-sn-甘油-3-磷胆碱、1,2-二-o -十八烷基-sn-甘油-3-磷胆碱、1,2-二-o -十八烷基-sn-甘油-3-磷乙醇双层中脂质共振的1H NMR化学位移显示出吲哚双峰分布，当吲哚存在时，吲哚位于脂质碳氢链/甘油区上部，靠近胆碱基团。吲哚-d(7)-结合的脂质双分子层的H-2 NMR显示，前者的位置被大约三分之二的吲哚占据，相对于双分子层的正常方向，吲哚采用明显的优先取向。结果表明，烃链上部/甘油的位置受多种因素的影响，包括与电荷和偶极子的相互作用、范德华相互作用、熵贡献和氢键。吲哚在含酯键的脂质中扩散速率更高，而在含胆碱的脂质中扩散速率更低，这表明吲哚和羰基之间的相互作用对脂质-吲哚结合的重要性较小，而与胆碱的阳离子- π相互作用驱动了吲哚的第二个位置。核Overhauser效应光谱交叉弛豫率表明吲哚-脂质结合的寿命为30ns。这些结果可能对富含色氨酸的膜蛋白的侧边性和结构转变具有重要意义。
The role of electrostatic forces in indole-lipid interactions was studied by H-1 and H-2 NMR in ether- and ester-linked phospholipid bilayers with incorporated indole. Indole-ring-current-induced 1H NMR chemical shifts of lipid resonances in bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-di-O-octadecenyl-sn-glycero-3-phosphocholine, and 1,2-di-O-octadecenyl-sn-glycero-3-phosphomethanol show a bimodal indole distribution, with indole residing at the upper hydrocarbon chain/glycerol region of the lipid and near the choline group, when present. H-2 NMR of indole-d(7)-incorporated lipid bilayers reveals that the former site is occupied by about two-thirds of the indole, which adopts a distinct preferred orientation with respect to the bilayer normal. The results suggest that the upper hydrocarbon chain/ glycerol location is dictated by many factors, including interactions with the electric charges and dipoles, van der Waals interactions, entropic contributions, and hydrogen bonding. Indole diffusion rates are higher in lipids with ester bonds and lower in choline-containing lipids, suggesting that interactions between indole and carbonyl groups are of minor importance for lipid-indole association and that cation-pi interactions with choline drive the second indole location. Nuclear Overhauser effect spectroscopy cross-relaxation rates suggest a 30-ns lifetime for indole-lipid associations. These results may have important implications for sidedness and structural transitions in tryptophan-rich membrane proteins.