Structure and protein environment of the retinal chromophore in light- and dark-adapted bacteriorhodopsin studied by solid-state NMR.
Structure and protein environment of the retinal chromophore in light- and dark-adapted bacteriorhodopsin studied by solid-state NMR.
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DOI：
10.1021/bi00448a032
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发表时间：
1989-10
期刊：
影响因子：
2.9
通讯作者：
Steven O. Smith;§. Huub;J. M. D. Groot;R. Gebhard;IIJacques M. L. Courtin;J. Lugtenburg;Judith Herzfeld;R. G. Griffin
中科院分区：
文献类型：
--
作者：
Steven O. Smith;§. Huub;J. M. D. Groot;R. Gebhard;IIJacques M. L. Courtin;J. Lugtenburg;Judith Herzfeld;R. G. Griffin
我们以前的固态13 C NMR研究bR已被定向在表征的结构和蛋白质环境的视网膜生色团bR 568和bR 548，两个组件的暗适应蛋白。在本文中，我们扩展了这些研究，提出了固态NMR光谱的光适应bR（bR 568），并更详细地研究了化学位移各向异性的视网膜共振附近的紫罗兰酮环和席夫碱。获得bR 568的魔角旋转（MAS）13 C NMR光谱，其用在位置12-15处标记的视网膜特异性13 C再生，这允许在暗适应bR光谱中观察到的共振的归属。特别感兴趣的是13 C-13和13 C-15共振的归属。bR 568的13 C-15化学共振（160.0 ppm）是bR 548的13 C-15共振（163.3 ppm）的高场。这种差异归因于bR 568中Schiff碱与其相关抗衡离子之间的相互作用较弱。bR 568的13 C-13化学位移（164.8 ppm）接近于全反式-视黄醛质子化席夫碱（PSB）模型化合物的13 C-13化学位移（约162 ppm），而bR 548的13 C-13共振（168.7 ppm）为13-顺式PSB模型化合物的13 C-13共振的低场约7 ppm。bR 568和bR 548之间的13 C-13化学位移的差异与从席夫碱氮的相应15 N化学位移所预期的相反，并且可能是由于C13 = C14-C15键中的发色团的构象畸变。（250字处删节）
Our previous solid-state 13C NMR studies on bR have been directed at characterizing the structure and protein environment of the retinal chromophore in bR568 and bR548, the two components of the dark-adapted protein. In this paper, we extend these studies by presenting solid-state NMR spectra of light-adapted bR (bR568) and examining in more detail the chemical shift anisotropy of the retinal resonances near the ionone ring and Schiff base. Magic angle spinning (MAS) 13C NMR spectra were obtained of bR568, regenerated with retinal specifically 13C labeled at positions 12-15, which allowed assignment of the resonances observed in the dark-adapted bR spectrum. Of particular interest are the assignments of the 13C-13 and 13C-15 resonances. The 13C-15 chemical resonance for bR568 (160.0 ppm) is upfield of the 13C-15 resonance for bR548 (163.3 ppm). This difference is attributed to a weaker interaction between the Schiff base and its associated counterion in bR568. The 13C-13 chemical shift for bR568 (164.8 ppm) is close to that of the all-trans-retinal protonated Schiff base (PSB) model compound (approximately 162 ppm), while the 13C-13 resonance for bR548 (168.7 ppm) is approximately 7 ppm downfield of that of the 13-cis PSB model compound. The difference in the 13C-13 chemical shift between bR568 and bR548 is opposite that expected from the corresponding 15N chemical shifts of the Schiff base nitrogen and may be due to conformational distortion of the chromophore in the C13 = C14-C15 bonds.(ABSTRACT TRUNCATED AT 250 WORDS)