QM/MM calculations of retinal protein excited states: Investigating the mechanisms of color tuning

尽管蛋白质bR和Rh含有相同的发色团，即质子化的视黄醛席夫碱，但与分离的视黄醛的光谱相比，不同蛋白质基质中的吸收最大值发生不同的位移（ω copsin位移）。这是由于发色团与不同蛋白质口袋中的各种氨基酸的相互作用。此外，在蛋白质中的光异构化显着不同于在溶液中，其速度，反应坐标和量子产率。在这个项目中，我们研究的特定相互作用的蛋白质与生色团在其电子激发态。这些调查现在是可行的，因为直到最近才有足够分辨率的各种中间体的晶体结构，并已开发出适当的理论方法。本论文的目的是研究蛋白质口袋中氨基酸残基的空间和静电相互作用对生色团光学性质的影响。此外，将研究由于光循环期间蛋白质重排引起的光谱变化以及由于氨基酸序列突变引起的变化。

Although the proteins bR and Rh contain the same chromophore, a protonated retinal Schiff base, the absorption maxima are shifted differently in the different protein matrices compared to the spectrum of the isolated retinal (¿copsin shift ). This is due to the interaction of the chromophore with various amino acids in the different protein pockets. Further, the photoisomerization in the protein differs significantly from that in solution, concerning its velocity, the reaction coordinate and quantum yield.In this project we investigate the specific interactions of the proteins with the chromophore in its electronically excited state. These investigations are now feasible, since only recently crystal structures of various intermediates with sufficient resolution became available, and appropriate theoretical methods have been developed. The goal of this proposal is to investigate the influence of steric and electrostatic interactions of amino acid residues from the protein pocket an the optical properties of the chromophore. Further, the spectral changes due to rearrangement of the protein during the photo cycle and the changes due to mutations of the amino acid sequence will be investigated.