Resonance Energy Transfer in DNA Duplexes Labeled with Localized Dyes
Resonance Energy Transfer in DNA Duplexes Labeled with Localized Dyes
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DOI：
10.1021/jp5065006
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发表时间：
2014-12-18
影响因子：
3.3
通讯作者：
Melinger, Joseph S.
中科院分区：
文献类型：
--
作者：
Cunningham, Paul D.;Khachatrian, Ani;Melinger, Joseph S.
基于 DNA 的架构的日益成熟引起了人们对应用它们来创建光活性光采集和传感设备的极大兴趣。为了优化此类结构的效率，系统地检查了一系列染料标记的 DNA 双链体中的共振能量转移，其中供体-受体间隔从 0 到 16 个碱基对逐渐改变。使用双亚磷酰胺附着化学将花青染料定位在 DNA 上。利用稳态光谱、单对荧光、时间分辨荧光和超快双色泵浦探针方法来检查能量传递过程。研究发现，能量转移率对 Cy3 供体和 Cy5 受体染料分子之间的距离比效率测量更敏感。对于最接近的分离，观察到皮秒能量转移和接近统一的效率。我们的测量结果与基于染料标记 DNA 双链体结构模型的福斯特理论预测之间的比较表明，双亚磷酰胺键导致嵌入和非嵌入染料方向的分布。与福斯特理论预测的偏差表明点偶极近似对于少于 10 个碱基对的分离是失败的。对于少于四个碱基对的分离，观察到染料之间的相互作用改变了它们的光学特性并违反了福斯特理论的弱耦合假设，这表明核碱基的去除会导致 DNA 变形并导致增强的染料与染料相互作用。
The growing maturity of DNA-based architectures has raised considerable interest in applying them to create photoactive light harvesting and sensing devices. Toward optimizing efficiency in such structures, resonant energy transfer was systematically examined in a series of dye-labeled DNA duplexes where donor-acceptor separation was incrementally changed from 0 to 16 base pairs. Cyanine dyes were localized on the DNA using double phosphoramidite attachment chemistry. Steady state spectroscopy, single-pair fluorescence, time-resolved fluorescence, and ultrafast two-color pump-probe methods were utilized to examine the energy transfer processes. Energy transfer rates were found to be more sensitive to the distance between the Cy3 donor and Cy5 acceptor dye molecules than efficiency measurements. Picosecond energy transfer and near-unity efficiencies were observed for the closest separations. Comparison between our measurements and the predictions of Forster theory based on structural modeling of the dye-labeled DNA duplex suggest that the double phosphoramidite linkage leads to a distribution of intercalated and nonintercalated dye orientations. Deviations from the predictions of Forster theory point to a failure of the point dipole approximation for separations of less than 10 base pairs. Interactions between the dyes that alter their optical properties and violate the weak-coupling assumption of Foster theory were observed for separations of less than four base pairs, suggesting the removal of nucleobases causes DNA deformation and leads to enhanced dye-dye interaction.