Nanosecond to Submillisecond Dynamics in Dye-Labeled Single-Stranded DNA, As Revealed by Ensemble Measurements and Photon Statistics at Single-Molecule Level
Nanosecond to Submillisecond Dynamics in Dye-Labeled Single-Stranded DNA, As Revealed by Ensemble Measurements and Photon Statistics at Single-Molecule Level
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DOI：
10.1021/jp811122a
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发表时间：
2009-10-22
影响因子：
3.3
通讯作者：
Miyasaka, Hiroshi
中科院分区：
文献类型：
--
作者：
Kaji, Takahiro;Ito, Syoji;Miyasaka, Hiroshi
单分子和系综时间分辨荧光测量被应用于调查的单链DNA，ssDNA的构象动力学，连接与荧光素染料的C6接头，其中DNA和C6接头的运动影响系统的几何形状。通过对DNA序列中鸟嘌呤碱基光诱导电子转移荧光猝灭的系综测量，发现水溶液中存在三种主要构象：在荧光素激发态寿命内不受鸟嘌呤碱基影响的构象、在激发态寿命内荧光动态猝灭的构象和通过非荧光络合物导致快速猝灭的构象.利用单分子测量的光子间时间分布直方图和FCS自相关的系综测量获得的参数分析表明，这三种构象之间的相互转换发生在几百纳秒和几十微秒的两个特征时间常数上。通过将实验结果与分子动力学模拟结果相结合，讨论了将系综测量与单分子探测相结合用于较复杂的动力学运动的优点。
Single-molecule and ensemble time-resolved fluorescence measurements were applied for the investigation of the conformational dynamics of single-stranded DNA, ssDNA, connected with a fluorescein dye by a C6 linker, where the motions both of DNA and the C6 linker affect the geometry of the system. From the ensemble measurement of the fluorescence quenching via photoinduced electron transfer with a guanine base in the DNA sequence, three main conformations were found in aqueous Solution: a conformation unaffected by the guanine base in the excited state lifetime of fluorescein, a conformation in which the fluorescence is dynamically quenched ill the excited-state lifetime, and a conformation leading to rapid quenching via nonfluorescent complex. The analysis by using the parameters acquired from the ensemble measurements for interphoton time distribution histograms and FCS autocorrelations by the single-molecule measurement revealed that interconversion ill these three conformations took place with two characteristic time constants of several hundreds of nanoseconds and tens of microseconds. The advantage of the combination use of the ensemble measurements with the single-molecule detections for rather complex dynamic motions is discussed by integrating the experimental results with those obtained by Molecular dynamics simulation.