Chemical and protein shifts in the spectrum of the photoactive yellow protein: a time-dependent density functional theory/molecular mechanics study
Chemical and protein shifts in the spectrum of the photoactive yellow protein: a time-dependent density functional theory/molecular mechanics study
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DOI：
10.1039/b902615k
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Molteni, Carla
中科院分区：
文献类型：
--
作者：
Gonzalez, Eneritz Muguruza;Guidoni, Leonardo;Molteni, Carla
采用含时密度泛函理论/分子力学（TDDFT/MM）方法研究了光敏黄蛋白（PYP）中对香豆酸生色团的光吸收性质.为了严格评估TDDFT对这个特定系统的性能，我们首先在真空中评估了几种PYP发色团模型的激发态。然后，我们计算了蛋白质中硫代甲基-对香豆酸（TMpCA（-））的酚阴离子的最大吸收。虽然在描述电荷转移和共振激发态的TDDFT的限制内，我们确认由于游离发色团和蛋白质之间的化学差异，在吸收最大值中有相当大的红移。发色团和蛋白质环境之间的相互作用引起非常小的光谱偏移，与实验证据一致。在真空中的发色团和在蛋白质中的垂直电子脱离能量之间的比较表明，蛋白质稳定的choromophore在激发态，通过防止自由基的形成。
We have studied the light absorption properties of the p-coumaric acid chromophore in the photoactive yellow protein (PYP) with a hybrid time-dependent density functional theory/molecular mechanics (TDDFT/MM) method. To critically assess the performance of TDDFT for this specific system, we first evaluated in vacuo the excited states of several PYP chromophore models. We then calculated the absorption maximum of the phenolate anion of the thiomethyl-p-coumaric acid (TMpCA(-)) in the protein. Although within the limitations of TDDFT in describing charge-transfer and resonance excited states, we confirm a sizeable red shift in the absorption maximum due to the chemical differences between the free chromophore and that in the protein. The interaction between the chromophore and the protein environment induces a very small spectral shift, in line with experimental evidence. Comparison between the vertical electron detachment energy of the chromophore in vacuo and in the protein reveals that the protein stabilizes the choromophore in the excited states by preventing radical formation.