物理化学学报 >> 2010, Vol. 26 >> Issue (04): 1087-1092.doi: 10.3866/PKU.WHXB20100408

生物物理化学 上一篇    下一篇

最大熵法分析寡聚核苷酸链内碰撞的荧光相关光谱

尹延东, 周晓雪, 赵新生   

  1. 北京大学化学与分子工程学院化学生物学系, 分子动态与稳态结构国家重点实验室, 北京分子科学国家实验室, 北京 100871
  • 收稿日期:2009-10-26 修回日期:2009-12-23 发布日期:2010-04-02
  • 通讯作者: 赵新生 E-mail:zhaoxs@pku.edu.cn

Maximum Entropy Method for Analyses of Fluorescence Correlation Spectra of Oligonucleotide Intra-Chain Collision

YIN Yan-Dong, ZHOU Xiao-Xue, ZHAO Xin-Sheng   

  1. Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2009-10-26 Revised:2009-12-23 Published:2010-04-02
  • Contact: ZHAO Xin-Sheng E-mail:zhaoxs@pku.edu.cn

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摘要：

准确地由荧光相关光谱(FCS)的实验数据提取动力学信息一直是一个挑战. 本文对比了三种主要的方法: 依赖于模型的多指数函数法, 经验的拓展指数函数法和不依赖于模型的最大熵法. 多指数函数法的物理意义直接但在复杂体系中难以应用和解释. 拓展指数函数法简单易行但其物理意义含混不清. 最大熵法不依赖于具体的物理模型但拟合结果对实验噪音很敏感. 经研究我们发现一个好的选择是将最大熵法和多指数函数法结合在一起使用. 对寡聚核苷酸链内碰撞荧光相关光谱的研究发现, 在单链DNA中可以形成碱基对时, 有两个并行的链内碰撞反应. 以前的拓展指数函数法分析则不能提供这样的信息. 我们建议在荧光相关光谱研究中审慎地使用最大熵法.

关键词: 荧光相关光谱, 弛豫时间分布, 拓展指数函数, 最大熵法, 寡聚核苷酸, 光致电子转移

Abstract:

It has been a challenge to accurately extract dynamic information from experimental fluorescence correlation spectroscopy (FCS) data. In this paper, we compare three major fitting methods: the model-dependent multiple exponential function (MultiExp), the empirical stretched exponential function (StreExp), and the exponential function based on the model-free maximumentropy method (MemExp). MultiExp has straight forward physical significance but it is difficult to implement and interpret in a complex system. StreExp has simple form and is easy to use but its physical picture is obscure. MultiExp is model free but its results are sensitive to experimental noise. A good choice seems to be a combination of MemExp and MultiExp. In our example, we have unraveled that two independent processes exist in the intra-chain collision of a single-stranded DNA when base pair formation is possible, which has not been observed by previous investigators. MemExp is recommended for the FCS data analysis, although caution should be exercised in the practice.

Key words: Fluorescence correlation spectroscopy, Relaxation time distribution, Stretched exponential function, Maximumentropy method, Oligonucleotide, Photoinduced electron transfer