Reconciliation of chemical, enzymatic, spectroscopic and computational data to assign the absolute configuration of the DNA base lesion spiroiminodihydantoin.
Reconciliation of chemical, enzymatic, spectroscopic and computational data to assign the absolute configuration of the DNA base lesion spiroiminodihydantoin.
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DOI：
10.1021/ja409254z
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发表时间：
2013-12-04
影响因子：
15
通讯作者：
Burrows CJ
中科院分区：
文献类型：
--
作者：
Fleming AM;Orendt AM;He Y;Zhu J;Dukor RK;Burrows CJ
由2′-脱氧鸟苷（dG）或8-氧代-7，8-二氢-2 ′-脱氧鸟苷（dOG）氧化产生的非对映体螺亚氨基二乙内酰脲-2 ′-脱氧核糖核苷（dSp）损伤由于其高度的致突变性而引起广泛关注。它们的螺旋桨状形状导致这些分子在体内显示立体化学依赖的突变谱。然而，存在冲突的绝对配置分配所产生的电子圆二色性（ECD）和NOESY-NMR实验，因此，提供明确的分配这些分子的三维结构是非常感兴趣的。在目前的工作中，我们提出的数据不一致的报告ECD分配的dSp非对映异构体在核苷的情况下，其中第一个洗脱的异构体从Hypercarb HPLC柱被分配为S构型和第二个被分配的R构型。进行了以下实验：（1）在手性杂化或螺旋桨G-四链体中，当dG单电子氧化时，dSp产物的非对映体比率的测定，所述手性杂化或螺旋桨G-四链体分别将re或si面暴露于溶剂，（2）使用振动圆二色性（VCD）光谱的绝对构型分析，（3）用含时密度泛函理论（TDDFT）重新解释了在Sp自由基周围的12个明显的氢键沃茨，（4）在TDDFT计算中使用水合模型重新评估Sp对映体的计算比旋光度。这些新的见解提供了对dSp非对映异构体的绝对构型归属的新看法，其中从Hypercarb-HPLC柱洗脱的第一个是（-）-（R）-dSp，第二个是（+）-（S）-dSp。这些任务现在提供了基础，了解立体化学依赖的酶，处理这种形式的DNA损伤的生物学意义。
The diastereomeric spiroiminodihydantoin-2′-deoxyribonucleoside (dSp) lesions resulting from 2′-deoxyguanosine (dG) or 8-oxo-7,8-dihydro-2′-deoxyguanosine (dOG) oxidation have generated much attention due to their highly mutagenic nature. Their propeller-like shape leads these molecules to display mutational profiles in vivo that are stereochemically dependent. However, there exist conflicting absolute configuration assignments arising from electronic circular dichroism (ECD) and NOESY-NMR experiments; thus, providing definitive assignments of the 3D structure of these molecules is of great interest. In the present body of work, we present data inconsistent with the reported ECD assignments for the dSp diastereomers in the nucleoside context, in which the first eluting isomer from a Hypercarb HPLC column was assigned to be the S configuration and the second was assigned the R configuration. The following experiments were conducted: (1) Determination of the diastereomer ratio of dSp products upon one-electron oxidation of dG in chiral hybrid or propeller G-quadruplexes that expose the re or si face to solvent, respectively, (2) absolute configuration analysis using vibrational circular dichroism (VCD) spectroscopy, (3) reinterpretation of the ECD experimental spectra using time-dependent density functional theory (TDDFT) with the inclusion of 12 explicit H-bonding waters around the Sp free bases, and (4) reevaluation of calculated specific rotations for the Sp enantiomers using the hydration model in the TDDFT calculations. These new insights provide a fresh look at the absolute configuration assignments of the dSp diastereomers in which the first eluting from a Hypercarb-HPLC column is (-)-(R)-dSp and the second is (+)-(S)-dSp. These assignments now provide the basis for understanding the biological significance of the stereochemical dependence of enzymes that process this form of DNA damage.
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影响因子：
3.8
作者：
Bandaru, Viswanath;Zhao, Xiaobei;Wallace, Susan S.
通讯作者：
Wallace, Susan S.
影响因子：
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作者：
Bauernschmitt, R;Ahlrichs, R
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Ahlrichs, R
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Geacintov, Nicholas E.
影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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