Maslennikov I V, Lugovskoĭ A A, Arsen'ev A S, Chikin L D, Ivanov V T
Bioorg Khim. 1997 Oct;23(10):771-82.
The [Nle18]-(87-136)-bacterioopsin, a fragment of bacterioopsin from Halobacterium salinarium synthesized by solid phase technique, was solubilized in a 1:1 chloroform-methanol mixture containing 0.1 M LiClO4 and studied by two-dimensional 1H NMR spectroscopy. The complete assignment of proton resonances was performed in the DQF-COSY, TOCSY, and NOESY spectra of this peptide, and its spatial structure was computed. As a result, two helical regions (92-100 and 108-130) were identified, which correspond to the C-terminal part of segment C and to segment D of bacteriorhodopsin, respectively. The 92-100 region forms a right-handed alpha-helix, and the 108-130 region can adopt right-handed alpha-helical, 3(10)-helical, and combined (from the two) conformations. A comparison of the structure computed with the bacteriorhodopsin model deduced from the electron cryomicroscopy data showed good agreement in the 91-100 region (the root-mean-square deviation of the backbone atoms was less than 0.51 A) and considerable differences in the 108-130 region (1.82 A). A dynamic model of the conformation of the D transmembrane segment was suggested, and the accordance of the model to the functional dynamics of bacteriorhodopsin was discussed.
通过固相技术合成的来自盐生盐杆菌的细菌视紫红质片段[Nle18]-(87-136)-细菌视紫红质，溶解于含有0.1 M高氯酸锂的氯仿-甲醇1:1混合物中，并通过二维1H NMR光谱进行研究。在该肽的DQF-COSY、TOCSY和NOESY光谱中完成了质子共振的完全归属，并计算了其空间结构。结果，鉴定出两个螺旋区域（92-100和108-130），它们分别对应于细菌视紫红质C片段的C末端部分和D片段。92-100区域形成右手α-螺旋，108-130区域可以采用右手α-螺旋、3(10)-螺旋以及两者组合的构象。将计算得到的结构与从电子低温显微镜数据推导的细菌视紫红质模型进行比较，结果显示在91-100区域一致性良好（主链原子的均方根偏差小于0.51 Å），而在108-130区域存在显著差异（1.82 Å）。提出了D跨膜片段构象的动力学模型，并讨论了该模型与细菌视紫红质功能动力学的一致性。
