Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany.
Phys Chem Chem Phys. 2011 Aug 28;13(32):14775-83. doi: 10.1039/c1cp21386e. Epub 2011 Jul 12.
The photophysics of roseoflavin in three different environments is investigated by using ab initio and quantum mechanics/molecular mechanics methods. Intramolecular charge transfer is shown to be responsible for the quenching of the fluorescence in the gas phase, and in the water environment. However, for the roseoflavin incorporated into the blue light using flavin (BLUF) protein environment (substituting the native flavin) no such deactivation is found. The conical intersection between the locally excited state of the chromophore and the charge transfer state involving the tyrosine residue, which in the native BLUF domain is responsible for initiating the photocycle, is missing for the roseoflavin substituted protein. This explains the experimental observations of the lack of any photocycle, and the loss of the biological function of the BLUF photoreceptor reported earlier.
通过使用从头算和量子力学/分子力学方法研究了玫瑰黄素在三种不同环境中的光物理性质。结果表明，分子内电荷转移是导致气相和水相中荧光猝灭的原因。然而，对于结合到蓝光利用黄素（BLUF）蛋白环境中的玫瑰黄素（取代天然黄素），则没有发现这种失活现象。在天然 BLUF 结构域中，发色团的局域激发态和涉及酪氨酸残基的电荷转移态之间的锥形交叉对于启动光循环是至关重要的，但对于取代蛋白来说，这种交叉是不存在的。这解释了实验观察到的缺乏任何光循环以及先前报道的 BLUF 光感受器生物功能丧失的现象。
