Effect of Protein Environment on Electronically Excited and Ionized States of the Green Fluorescent Protein Chromophore
Effect of Protein Environment on Electronically Excited and Ionized States of the Green Fluorescent Protein Chromophore
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DOI：
10.1021/jp2020269
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发表时间：
2011-06-30
影响因子：
3.3
通讯作者：
Krylov, Anna I.
中科院分区：
文献类型：
--
作者：
Bravaya, Ksenia B.;Khrenova, Maria G.;Krylov, Anna I.
用量子力学/分子力学(QM/MM)方法研究了蛋白质环境对气相绿色荧光蛋白(GFP)发色团电子结构的影响。该蛋白质对绿色荧光蛋白基团的亮吸收和最低三重态的激发能影响很小，但使垂直分离能从气相去质子化4-hydroxybenzylidene-2，3-dimethylimidazolinone阴离子的2.5 eV增加到5.0 eV。我们还研究了与GFP发色团相关的电荷转移到溶剂(CTTS)态的可能存在。虽然这种状态的前体出现在团簇计算中，但蛋白质的紧密堆积结构阻止了该系统中CTTS状态的形成。受新近发现的一种新型光转化--氧化红化作用的启发，我们表征了GFP的氧化还原性质。计算的GFP阴离子形式的标准还原电位为0.47V(对于GFP(中心点)+LE->；GFP(-)反应)，在生理条件下(pH=7，T=25℃)还原电位为0.06V。
The effect of the protein environment on the electronic structure of the gas phase green fluorescent protein (GFP) chromophore is investigated by QM/MM (quantum mechanics/molecular mechanics) calculations. The protein has very small effect on the excitation energy of the bright absorbing and the lowest triplet states of the anionic GFP chromophore, deprotonated 4-hydroxybenzylidene-2,3-dimethylimidazolinone (HBDI) anion, however, it increases vertical detachment energy from 2.5 eV (gas-phase deprotonated HBDI anion) to 5.0 eV (solvated protein). We also investigated possible existence of the charge-transfer-to-solvent (CTTS) states associated with the GFP chromophore. Although precursors of such states appear in cluster calculations, a tightly packed structure of the protein prevents the formation of the CTTS states in this system. Motivated by a recently discovered new type of photoconversion, oxidative redding, we characterized the redox properties of GFP. The computed standard reduction potential of the anionic form of GFP is 0.47 V (for the GFP(center dot) + le -> GFP(-) reaction), and the reduction potential at physiological conditions (pH 7, T = 25 degrees C) is 0.06 V.