Gopich Irina V, Szabo Attila
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Phys Chem B. 2009 Aug 6;113(31):10965-73. doi: 10.1021/jp903671p.
Conformational dynamics of a single molecule can be studied using Forster resonance energy transfer (FRET) by recording a sequence of photons emitted by a donor and an acceptor dye attached to the molecule. We describe a simple and robust method to estimate the rates of transitions between different conformational states and the FRET efficiencies associated with these states. For a photon trajectory with measured interphoton times, the pattern of colors is decoded by maximizing the appropriate likelihood function. This approach can be used to analyze bursts of photons from diffusing molecules as well as photon trajectories generated by immobilized molecules. The procedure is illustrated using simulated photon trajectories corresponding to two-state and three-state molecules. The method works even when the photon colors appear to be scrambled because of high background noise, the photophysical properties of the conformers are similar, or the conformational and photon count rates are comparable. The consistency of the model with the data can be checked by recoloring the photon trajectories and comparing the predicted and observed FRET efficiency histograms.
单分子的构象动力学可以通过福斯特共振能量转移（FRET）来研究，方法是记录附着在分子上的供体和受体染料发射的一系列光子。我们描述了一种简单而稳健的方法，用于估计不同构象状态之间的转变速率以及与这些状态相关的FRET效率。对于具有测量光子间隔时间的光子轨迹，通过最大化适当的似然函数来解码颜色模式。这种方法可用于分析扩散分子发出的光子爆发以及固定分子产生的光子轨迹。使用对应于二态和三态分子的模拟光子轨迹来说明该过程。即使由于高背景噪声导致光子颜色看起来混乱、构象异构体的光物理性质相似或构象和光子计数率相当，该方法也能起作用。通过对光子轨迹重新着色并比较预测和观察到的FRET效率直方图，可以检查模型与数据的一致性。
