Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, A-1180 Vienna, Austria.
Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währinger Straße 17, A-1180 Vienna, Austria.
J Phys Chem Lett. 2020 Dec 3;11(23):10212-10218. doi: 10.1021/acs.jpclett.0c03070. Epub 2020 Nov 18.
The urge to discover selective fluorescent binders to G-quadruplexes (G4s) for rapid diagnosis must be linked to understand the effect that those have on the DNA photophysics. Herein, we report on the electronic excited states of a bound merocyanine dye to c-Myc G4 using extensive multiscale quantum mechanics/molecular mechanics calculations. We find that the absorption spectra of c-Myc G4, both without and with the intercalated dye, are mainly composed of exciton states and mixed local/charge-transfer states. The presence of merocyanine hardly affects the energy range of the guanine absorption or the number of guanines excited. However, it triggers a substantial amount (16%) of detrimental pure charge-transfer states involving oxidized guanines. We identify the rigidity introduced by the probe in G4, reducing the overlap among guanines, as the one responsible for the changes in the exciton and charge-transfer states, ultimately leading to a redshift of the absorption maximum.
探索选择性荧光结合物以快速诊断 G-四链体（G4s）的冲动必须与理解这些结合物对 DNA 光物理的影响联系起来。在此，我们使用广泛的多尺度量子力学/分子力学计算报告了结合到 c-Myc G4 的甲川花菁染料的电子激发态。我们发现，c-Myc G4 的吸收光谱，无论是没有还是与嵌入的染料一起，主要由激子态和混合的局部/电荷转移态组成。甲川花菁的存在几乎不会影响鸟嘌呤的吸收能区或激发的鸟嘌呤的数量。然而，它会引发大量（16%）涉及氧化鸟嘌呤的有害纯电荷转移态。我们确定了探针在 G4 中引入的刚性，减少了鸟嘌呤之间的重叠，这是导致激子和电荷转移态变化的原因，最终导致吸收最大值的红移。
