Braiman M, Mathies R
Biochemistry. 1980 Nov 11;19(23):5421-8. doi: 10.1021/bi00564a042.
Using a dual-beam flow technique, we have obtained resonance Raman spectra of the M412 photointermediates of both native purple membrane (15H M412) and purple membrane regenerated with 15-deuterioretinal (15D M412). For comparison, we have also obtained Raman spectra of the n-butylamine Schiff bases of the 13-cis and all-trans isomers of 15H and 15D retinal. The 15D model compound spectra, when compared to the 15H spectra, show isotopically induced spectral changes that are markedly different for the two isomers. There is a very close agreement between the frequency and intensity changes which occur upon deuteration of M412 and those which occur upon deuteration of the 13-cis model compound, but not even a qualitative correspondence exists when M412 and the all-trans model compound are similarly compared. These data demonstrate that the chromophore of M412 is an unprotonated Schiff base of 13-cis-retinal rather than all-trans-retinal. An analogous spectral comparison of 15H and 15D light-adapted bacteriorhodopsin (bRLA) with the 15H and 15D protonated Schiff bases of 13-cis- and all-trans-retinal demonstrates that bRLA contains an all-trans chromophore, in agreement with previous extraction experiments. Thus, a trans leads to cis isomerization occurs in the proton-pumping photocycle of Halobacterium halobium.
我们使用双光束流动技术，获得了天然紫膜（15H M412）和用15-氘代视黄醛再生的紫膜（15D M412）的M412光中间体的共振拉曼光谱。为了进行比较，我们还获得了15H和15D视黄醛的13-顺式和全反式异构体的正丁胺席夫碱的拉曼光谱。与15H光谱相比，15D模型化合物光谱显示出同位素诱导的光谱变化，这两种异构体明显不同。M412氘代时发生的频率和强度变化与13-顺式模型化合物氘代时发生的变化非常吻合，但当对M412和全反式模型化合物进行类似比较时，甚至不存在定性对应关系。这些数据表明，M412的发色团是13-顺式视黄醛的未质子化席夫碱，而不是全反式视黄醛。对15H和15D光适应细菌视紫红质（bRLA）与13-顺式和全反式视黄醛的15H和15D质子化席夫碱进行类似的光谱比较表明，bRLA含有全反式发色团，这与先前的提取实验一致。因此，在嗜盐菌的质子泵浦光循环中发生了反式到顺式的异构化。
