Matute Ricardo A, Contreras Renato, Pérez-Hernández Guillermo, González Leticia
J Phys Chem B. 2008 Dec 25;112(51):16253-6. doi: 10.1021/jp807471e.
The UV-vis absorption spectra of the photoreceptor chromophores biliverdin (BV) in the ZZZssa conformation and the phycocyanobilin (PCB) with conformations ZZZssa and ZZZasa have been investigated by means of time-dependent density functional theory (TD-DFT) with a polarized continuum model. The three systems are studied in different conditions to include protonation, solvation- and protein-environmental effects on gas phase and available X-ray structures. The crystal structures of BV in bacteriophytochrome of Deinococcus radiodurans and PCB in C-Phycocyanin serve to calibrate the performance of the TD-DFT method and allow estimating the spectral shifts created when gas phase structures instead of a proper environment are used. In contrast, the structure of PCB in the cyanobacterial phytochrome Cphl is unknown. The excellent agreement of the theoretical spectrum with experimentally recorded data for the PCB in the cyanobacterial phytochrome Cph1 strongly supports a semicyclic ZZZssa structure, similar to that found for the BV chromophore.
通过含极化连续介质模型的含时密度泛函理论（TD-DFT），研究了处于ZZZssa构象的光感受器发色团胆绿素（BV）以及具有ZZZssa和ZZZasa构象的藻蓝胆素（PCB）的紫外可见吸收光谱。对这三个体系在不同条件下进行了研究，包括质子化、溶剂化以及气相和可用X射线结构上的蛋白质环境效应。耐辐射球菌的细菌光敏色素中BV的晶体结构以及藻蓝蛋白中PCB的晶体结构用于校准TD-DFT方法的性能，并允许估计使用气相结构而非合适环境时产生的光谱位移。相比之下，蓝藻光敏色素Cphl中PCB的结构未知。理论光谱与蓝藻光敏色素Cph1中PCB的实验记录数据的出色吻合有力地支持了一种半环状的ZZZssa结构，类似于在BV发色团中发现的结构。
