TRYPTOPHAN DYNAMICS AND STRUCTURAL REFINEMENT IN A LIPID BILAYER ENVIRONMENT - SOLID-STATE NMR OF THE GRAMICIDIN CHANNEL
TRYPTOPHAN DYNAMICS AND STRUCTURAL REFINEMENT IN A LIPID BILAYER ENVIRONMENT - SOLID-STATE NMR OF THE GRAMICIDIN CHANNEL
复制标题
DOI：
10.1021/bi00043a019
复制
发表时间：
1995-10-31
期刊：
影响因子：
2.9
通讯作者：
CROSS, TA
中科院分区：
文献类型：
--
作者：
HU, W;LAZO, ND;CROSS, TA
短杆菌肽通道中的色氨酸对于确定相对于双层法线的构象和取向以及促进阳离子电导是重要的。在这里，这些环的高分辨率结构和动力学的特点是固态NMR。使用定向和非定向脂质双层制剂。非取向样品的快速冷冻脂质双层制剂已被用于获得核自旋相互作用张量的静态表征。这些未取向的样品的温度依赖性和快速冻结的取向样品的光谱特征被用来实验定义的个别吲哚环的局部运动。局部运动的振幅高达+/-29度，并且运动主要是围绕chi（2）轴的天平动。高分辨率的结构已经实现了解释7个精确的（+/-0.3度）取向的限制，从H-2和N-15 NMR的每个吲哚环的光的运动平均相互作用张量。四种吲哚中的每一种都被限制在相对于双层法线的环的唯一取向和两种可能的旋转异构状态之一，每个残基的侧链扭转角非常相似，相对于通道产生类似的电偶极矩取向。
Tryptophans in the gramicidin channel are important for defining the conformation and the orientation with respect to the bilayer normal and for facilitating cation conductance. Here, high-resolution structure and dynamics of these rings are characterized by solid state NMR. Both oriented and unoriented lipid bilayer preparations are used. Fast frozen lipid bilayer preparations of unoriented samples have been used to obtain static characterizations of nuclear spin interaction tensors. The temperature dependence of these unoriented samples and the spectral features of fast frozen oriented samples were used to experimentally define the local motions of the individual indole rings. Local motions were shown to have amplitudes as high as +/-29 degrees, and the motions were dominated by libration about the chi(2) axis. The high-resolution structure has been achieved by interpreting seven precise (+/-0.3 degrees) orientational constraints from H-2 and N-15 NMR for each indole ring in light of the motionally averaged interaction tensors. Each of the four indoles is restricted to a unique orientation of the ring with respect to the bilayer normal and one of two possible rotameric states, The side chain torsion angles for each residue are very similar, generating similar electric dipole moment orientations with respect to the channel.