The Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
Phys Chem Chem Phys. 2011 Jan 28;13(4):1585-9. doi: 10.1039/c0cp01075h. Epub 2010 Dec 6.
Using advanced QM/MM methods, the surprisingly negligible shift of the lowest-lying bright electronic excitation of the deprotonated p-coumaric acid (pCA(-)) within the photoactive yellow protein (PYP) is shown to stem from a subtle balance between hypsochromic and bathochromic effects. More specifically, it is found that the change in the excitation energy as a consequence of the disruption of the planarity of pCA(-) inside PYP is nearly canceled out by the shift induced by the intermolecular interactions of the chromophore and the protein as a whole. These results provide important insights about the primary absorption and the tuning of the chromophore by the protein environment in PYP.
利用先进的QM/MM 方法，研究表明，在光致变色黄色蛋白（PYP）中，去质子化对香豆酸（pCA(-)）的最低亮电子激发的惊人可忽略的位移源于蓝移和红移效应之间的微妙平衡。更具体地说，研究发现，由于 pCA(-)在 PYP 中的平面性被破坏而导致的激发能量的变化几乎被发色团和整个蛋白质之间的分子间相互作用所诱导的位移所抵消。这些结果为 PYP 中蛋白质环境对发色团的初始吸收和调谐提供了重要的见解。
