Conformation and dynamics of melittin bound to magnetically oriented lipid bilayers by solid-state 31P and 13C NMR spectroscopy
Conformation and dynamics of melittin bound to magnetically oriented lipid bilayers by solid-state 31P and 13C NMR spectroscopy
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DOI：
10.1016/s0006-3495(00)76784-1
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发表时间：
2000-05-01
影响因子：
3.4
通讯作者：
Saitô, H
中科院分区：
文献类型：
--
作者：
Naito, A;Nagao, T;Saitô, H
用固体核磁共振谱研究了蜂毒肽与二肉豆蔻酰磷脂酰胆碱（DMPC）双层膜结合的构象和动力学以及在脂双层系统中的磁取向。使用P-31 NMR，发现蜂毒肽-脂质双层在高于液晶-凝胶相变温度（Tm = 24 ℃）时形成具有平行于磁场的长轴的磁性取向的细长囊泡。蜂毒肽结合到膜的构象，取向和动力学进一步确定通过使用这种磁性取向的脂质双层系统。为此，在静态、快速魔角旋转（MAS）和慢速MAS条件下测量了与膜结合的位点特异性C-13-标记蜂毒肽的C-13 NMR谱。随后，我们分析了C-13化学位移张量的羰基碳的肽骨架的条件下，他们形成一个α-螺旋和重新定位的平均螺旋轴。最后，发现蜂毒肽采用跨膜α-螺旋，其平均轴平行于双层法线。在脂双层中蜂毒肽的N-和C-末端螺旋杆之间的扭结角类似于140度或类似于160度，其大于通过X射线衍射研究确定的120度的值。在显微镜下，在裂解的初始阶段，在T-m以下清楚地观察到孔形成。这被认为是由蜂毒肽分子在脂质双层中的缔合引起的。
The conformation and dynamics of melittin bound to the dimyristoylphosphatidylcholine (DMPC) bilayer and the magnetic orientation in the lipid bilayer systems were investigated by solid-state P-31 and C-13 NMR spectroscopy. Using P-31 NMR, it was found that melittin-lipid bilayers form magnetically oriented elongated vesicles with the long axis parallel to the magnetic field above the liquid crystalline-gel phase transition temperature (T-m = 24 degrees C). The conformation, orientation, and dynamics of melittin bound to the membrane were further determined by using this magnetically oriented lipid bilayer system. For this purpose, the C-13 NMR spectra of site-specifically C-13-labeled melittin bound to the membrane in the static, fast magic angle spinning (MAS) and slow MAS conditions were measured. Subsequently, we analyzed the C-13 chemical shift tensors of carbonyl carbons in the peptide backbone under the conditions where they form an alpha-helix and reorient rapidly about the average helical axis. Finally, it was found that melittin adopts a transmembrane alpha-helix whose average axis is parallel to the bilayer normal. The kink angle between the N- and C-terminal helical rods of melittin in the lipid bilayer is similar to 140 degrees or similar to 160 degrees, which is larger than the value of 120 degrees determined by x-ray diffraction studies. Pore formation was clearly observed below the T-m in the initial stage of lysis by microscope. This is considered to be caused by the association of melittin molecules in the lipid bilayer.