The stereoisomerism of bacterial, reaction-center-bound carotenoids revisited: An electronic absorption, resonance Raman and 1H-NMR study
The stereoisomerism of bacterial, reaction-center-bound carotenoids revisited: An electronic absorption, resonance Raman and 1H-NMR study
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重新审视细菌反应中心结合类胡萝卜素的立体异构现象：电子吸收、共振拉曼和 1H-NMR 研究
DOI：
10.1016/0005-2728(87)90121-6
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
J. Neumann
中科院分区：
文献类型：
--
作者：
M. Lutz;W. Szponarski;G. Berger;B. Robert;J. Neumann
为了解决以前的任务之间的差异，我们重新研究了sphaeroides反应中心（RC）的spheroidene分子的立体异构性。通过在非常低的环境光下工作，可以从反应中心提取和纯化稳定的异构体。共振拉曼光谱表明，该顺式异构体的构型与RC结合的分子相同。提取的异构体的质子-NMR光谱允许指定它的15-15′ monocisconfiguration。共振拉曼光谱的天然形式和15 cisextract之间的比较表明，在反应中心，15 cisspheroidene是另外扭曲成非平面构象。提取引起的760-1060 cm− 1区域拉曼谱带相对强度的变化（主要对应于面外模式）的比较进一步表明，RC结合的类球体的面外扭曲应该主要影响分子的C8-C12和/或C8′-C12′区域，而不是中心区域。通过对RC键合的类球烯和甲氧基脉孢烯的电子吸收光谱的比较，发现这两种天然形式的离面扭曲导致它们的1C ←1A电子跃迁比平面15顺式的电子跃迁明显减弱。最后，根据它们的共振拉曼光谱，提出了红杜鹃红细胞上的类胡萝卜素以及绿红杜鹃红细胞上的二氢神经孢烯和二氢番茄红素与不同株红细胞上的类胡萝卜素呈15顺式构型和面外扭曲。sphaeroides
In order to solve discrepancies between earlier assignments we have reinvestigated the stereoisomerism of the spheroidene molecule bound to reaction centers (RC) ofRhodobacter sphaeroides. A stablecisisomer could be extracted and purified from the reaction centres by working at very low ambient light. Resonance Raman spectroscopy showed that thiscisisomer assumed the same configuration as that of the RC-bound molecule. Proton-NMR spectroscopy of the extracted isomer permitted to assign it the 15–15′ monocisconfiguration. Comparisons between resonance Raman spectra of the native form and of the 15cisextract showed that, in the reaction center, 15cisspheroidene is in addition twisted into a non-planar conformation. Comparisons of extraction-induced changes in relative intensities of Raman bands of the 760–1060 cm−1regions, which largely correspond to out-of-plane modes, further indicated that the out-of-plane twist of RC-bound spheroidene should predominantly affect C8–C12and/or C8′–C12′regions of the molecule rather than the central region. Comparisons between difference electronic absorption spectra of RC-bound spheroidene and of RC-bound methoxyneurosporene showed that the out-of-plane twisting of both these native forms results in a drastic weakening of their1C ←1A electronic transitions, compared with those of the planar, 15cisforms. Finally, it is proposed, on the basis of their resonance Raman spectra, that spirilloxanthin bound to RCs ofRhodospirillum rubrumas well as dihydroneurosporene or dihydrolycopene bound to RCs ofRhodopseudomonas viridisshares 15cisconfigurations and out-of-plane twisting with carotenoids bound to RCs of various strains ofRb. sphaeroides.