Tuning the Quantum Chemical Properties of Flavins via Modification at C8
Tuning the Quantum Chemical Properties of Flavins via Modification at C8
复制标题
C8位修饰调控黄酮类化合物的量子化学性质
DOI：
10.1021/acs.jpcb.1c07306
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发表时间：
2021-11-25
影响因子：
3.3
通讯作者：
Miller, Anne-Frances
中科院分区：
文献类型：
--
作者：
Kar, Rajiv K.;Chasen, Sam;Miller, Anne-Frances
黄素是无数酶的核心，但根据环境的不同，表现出不同的反应活性。这被理解为反映了黄素电子结构的调制。为了了解环系上轨道性质、能量和相关性的变化，我们首先比较了七个在C8上不同的黄素变体，利用它们不同的电子光谱来验证量子化学计算。基态计算复制了Hammett趋势，并揭示了Flavin JR系统的重要性。高层理论的比较确立了CC2和ACD(2)作为表征电子跃迁的方法的选择。电荷转移特性和电子关联证明了C8上取代基的同一性。事实上，键长交替分析表明，在整个环系中，C8位置发生了广泛的共轭和离域作用。此外，通过在显性溶剂中实现混合QM/MM，我们成功地复制了一个特别具有挑战性的UV/Vis光谱。我们的计算表明，当8-甲基被NH_2、OH或SH取代时，非键孤子对的存在与观察到的UV/VIS光谱的变化有关。因此，我们的计算为理解不同修饰的黄素的光谱提供了途径。这是了解不同绑定环境如何实现相同功能的第一步。
Flavins are central to countless enzymes but display different reactivities depending on their environments. This is understood to reflect modulation of the flavin electronic structure. To understand changes in orbital natures, energies, and correlation over the ring system, we begin by comparing seven flavin variants differing at C8, exploiting their different electronic spectra to validate quantum chemical calculations. Ground state calculations replicate a Hammett trend and reveal the significance of the flavin Jr-system. Comparison of higher-level theories establishes CC2 and ACD(2) as methods of choice for characterization of electronic transitions. Charge transfer character and electron correlation prove responsive to the identity of the substituent at C8. Indeed, bond length alternation analysis demonstrates extensive conjugation and delocalization from the C8 position throughout the ring system. Moreover, we succeed in replicating a particularly challenging UV/Vis spectrum by implementing hybrid QM/MM in explicit solvents. Our calculations reveal that the presence of nonbonding lone pairs correlates with the change in the UV/Vis spectrum observed when the 8-methyl is replaced by NH2, OH, or SH. Thus, our computations offer routes to understanding the spectra of flavins with different modifications. This is a first step toward understanding how the same is accomplished by different binding environments.