Novel retinylidene iminium salts for defining opsin shifts: synthesis and intrinsic chromophoric properties
作者:Michael Åxman Petersen、Iben B. Nielsen、Michael B. Kristensen、Anders Kadziola、Lutz Lammich、Lars H. Andersen、Mogens Brøndsted Nielsen
DOI:10.1039/b600121a
日期:——
Retinal Schiff bases serve as chromophores in many photoactive proteins that carry out functions such as signalling and light-induced ion translocation. The retinal Schiff base can be found as neutral or protonated, as all-trans, 11-cis or 13-cis isomers and can adopt different conformations in the protein binding pocket. Here we present the synthesis and characterisation of isomeric retinylidene iminium salts as mimics blocked towards isomerisation at the C11 position and conformationally restrained. The intrinsic chromophoric properties are elucidated by gas phase absorption studies. These studies reveal a small blue-shift in the S0→S1 absorption for the 11-locked derivative as compared to the unlocked one. The gas phase absorption spectra of all the cationic mimics so far investigated show almost no absorption in the blue region. This observation stresses the importance of protein interactions for colour tuning, which allows the human eye to perceive blue light.
视网膜席夫碱是许多光活性蛋白质中的发色团,具有信号传递和光诱导离子转移等功能。视网膜席夫碱可以是中性的或质子化的,也可以是全反式、11-顺式或 13-顺式异构体,而且可以在蛋白质结合袋中采用不同的构象。在这里,我们介绍了异构亚视黄醛亚胺盐的合成和特性,它们是在 C11 位置阻断异构化并限制构象的模拟物。气相吸收研究阐明了其内在的色度特性。这些研究表明,与未锁定的衍生物相比,11-锁定衍生物的 S0→S1 吸收有微小的蓝移。迄今为止研究的所有阳离子模拟物的气相吸收光谱在蓝色区域几乎没有吸收。这一观察结果强调了蛋白质相互作用对色彩调谐的重要性,这使得人眼能够感知蓝光。