A resonance Raman study of the C=N configurations of octopus rhodopsin, bathorhodopsin, and isorhodopsin.
A resonance Raman study of the C=N configurations of octopus rhodopsin, bathorhodopsin, and isorhodopsin.
复制标题
对章鱼视紫红质、红视紫红质和异视紫红质的 C=N 构型的共振拉曼研究。
DOI：
10.1021/bi960638g
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Callender,RH
中科院分区：
文献类型：
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作者：
Huang,L;Deng,H;Weng,G;Koutalos,Y;Ebrey,T;Groesbeek,M;Lugtenburg,J;Tsuda,M;Callender,RH
在120 K下，我们获得了章鱼视紫红质、视紫红质和异视紫红质的共振拉曼光谱，以及在C14−C15键附近用同位素标记的视黄醇再生的色素的共振拉曼光谱。希夫碱氮的氘化导致1100 - 1300 cm-1之间的C-C伸缩区发生相对较大的变化，包括三种章鱼中位于1206 - 1227 cm-1的C14-C15伸缩模的较大频移，这一点由它们的14，15 - 13 C2衍生物的拉曼光谱揭示。这样的结果与牛色素的结果不同，牛色素在席夫碱N氘代后没有观察到C14−C15伸缩模的显著频移。在较早的一个席夫碱模型化合物的拉曼研究中，该模型化合物仅包含一个与两个双键相邻的单键，我们发现，当CN构型为反构型时，在席夫碱N氘代时，该C-C单键在1232 cm-1处的拉伸模式向上移动15 cm-1，并且其强度也大大降低[Deng et al.，（1994）J.Phys.Chem.98，4776 - 4779]。同样的研究还表明，当CN组态是syn时，C-C伸缩模应该在1150 cm-1左右。由于C14−C15伸缩模频率在章鱼视紫红质和视紫红质的光谱中相对较高（>1200 cm-1），并且由于席夫碱附近的正常模式与模型相似，我们认为这两种物种的CN构型是反的。C14−C15伸缩模式对牛和章鱼色素中席夫碱氮氘代反应的不同响应是由于模型化合物或牛视紫红质中的耦合C14−C15伸缩和C12−C13伸缩运动在章鱼视紫红质中发生了改变，使得C14−C15键的伸缩运动更加局部化，类似于小席夫碱模型化合物中的C-C拉伸运动。与牛视紫红质的拉曼光谱（与11-顺式-视黄酸席夫碱的拉曼光谱非常相似）形成鲜明对比的是，章鱼视紫红质的光谱截然不同，表明C11 C12 −C13部分上的蛋白质扰动很大，可能是空间作用，也可能是静电作用。需要进一步的研究来确定这种光谱差异是否表明这两种色素在初级光化学事件中的能量转换机制的差异。
The resonance Raman spectra of octopus rhodopsin, bathorhodopsin, and isorhodopsin at 120 K have been obtained as well as those of pigments regenerated with isotopically labeled retinals near the C14−C15 bond. Deuteration of the Schiff base nitrogen induces relatively large changes in the C−C stretch region between 1100 and 1300 cm-1, including a large frequency shift of the C14−C15 stretch mode located at 1206−1227 cm-1in the three octopus species, as revealed by the Raman spectra of their 14,15-13C2derivatives. Such results are different compared to those of the bovine pigments, in which no significant frequency shift of the C14−C15 stretch mode was observed upon Schiff base N deuteration. In an earlier Raman study of a Schiff base model compound which contained only one single bond adjacent to two double bonds, we have found that the stretch mode of this C−C single bond at 1232 cm-1shifts up by 15 cm-1and its intensity is also greatly reduced upon Schiff base N deuteration when the CN configuration is anti [Deng et al., (1994)J.Phys.Chem.98, 4776−4779]. The same study has also shown that when the CN configuration is syn, the C−C stretch mode should be at about 1150 cm-1. Since the C14−C15 stretch mode frequency is relatively high in the spectra of octopus rhodopsin and bathorhodopsin (>1200 cm-1) and since the normal mode pattern near the Schiff base is similar to the model, we suggest that the CN configuration in these two species is anti. The different responses of the C14−C15 stretch mode to the Schiff base nitrogen deuteration in bovine and octopus pigments are due to the fact that the coupled C14−C15 stretch and the C12−C13 stretch motions in the model compound or in bovine rhodopsin are altered in octopus rhodopsin so that the stretch motion of the C14−C15 bond is more localized, similar to the C−C stretch motion in the small Schiff base model compound. In clear contrast with the bovine rhodopsin Raman spectrum, which is very similar to that for the 11-cis-retinal Schiff base, the drastically different octopus rhodopsin spectrum indicates large protein perturbations on the C11C12−C13 moiety, either by steric or by electrostatic interactions. Further studies are required to determine if such spectral differences indicate a difference of the energy conversion mechanisms in the primary photochemical event of these two pigments.