Raman Optical Activity Reveals Carotenoid Photoactivation Events in the Orange Carotenoid Protein in Solution,Journal of the American Chemical Society

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Raman Optical Activity Reveals Carotenoid Photoactivation Events in the Orange Carotenoid Protein in Solution
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-07-21 00:00:00 , DOI: 10.1021/jacs.7b05193
Tomotsumi Fujisawa ₁ , Ryan L. Leverenz _{2,

3} , Momoka Nagamine ₁ , Cheryl A. Kerfeld _{2,

3} , Masashi Unno ₁

Affiliation

The orange carotenoid protein (OCP) plays an important role in photoprotection in cyanobacteria, which is achieved by the photoconversion from the orange dark state (OCP^O) to the red active state (OCP^R). Using Raman optical activity (ROA), we studied the conformations of the carotenoid chromophore in the active sites of OCP^O and OCP^R. This ROA measurement directly observed the chromophore conformation of native OCP in solution, and the measurement of OCP^R first demonstrated the ROA spectroscopy for the transient species. For OCP^O, the spectral features of ROA were mostly reproduced by the quantum chemical calculation based on the crystal structure of the OCP. Within the spatial resolution (∼2 Å), a slight modification of the polyene-chain distortion improved the agreement between the observed and calculated ROA spectra. While the crystal structure of OCP^R is not available, the ROA spectrum of OCP^R was reproduced by using the crystal structure of red carotenoid protein (RCP), an OCP^R proxy. The present results showed that the chromophore conformations in the crystal structures of OCP and RCP hold true for OCP^O and OCP^R in solution. Particularly, ROA spectroscopy of the native OCP^R provides a direct support for the 12 Å translocation of chromophore in the photoactivation, which was proposed by X-ray crystallography using RCP [R. L. Leverenz, M. Sutter, et al. Science 2015, 348, 1463–1466].

中文翻译：

拉曼光学活性揭示了溶液中橙色类胡萝卜素蛋白中的类胡萝卜素光活化事件

橙色类胡萝卜素蛋白（OCP）在蓝细菌的光保护中起着重要作用，这是通过从橙色暗态（OCP ^O）到红色活性态（OCP ^R）的光转化来实现的。使用拉曼光学活性（ROA），我们研究了OCP ^O和OCP ^R活性位点中类胡萝卜素发色团的构象。此ROA测量直接观察溶液中天然OCP的发色团构象，而OCP ^R的测量首先证明了该瞬态物质的ROA光谱。对于OCP ^O，ROA的光谱特征大部分是通过基于OCP晶体结构的量子化学计算再现的。在空间分辨率（〜2Å）范围内，多烯链畸变的轻微改变改善了观察到的和计算出的ROA光谱之间的一致性。而OCP的晶体结构^{- [R}不可用，OCP的ROA光谱^ř通过使用红色类胡萝卜素蛋白（RCP），一个OCP的晶体结构再现^ř代理。目前的结果表明，OCP和RCP晶体结构中的发色团构象对溶液中的OCP ^O和OCP ^R成立。特别是天然OCP ^R的ROA光谱X射线晶体学使用RCP [RL Leverenz，M. Sutter，et al。（2003）。]提出了光活化中生色团的12Å易位的直接支持。科学 2015年，348，1463年至1466年。

更新日期：2017-07-22

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