停流-圆二色谱法研究DNA i-motif的折叠与解折叠动力学

第一篇：停流-圆二色谱法研究DNA i-motif的折叠与解折叠动力学

停流-圆二色谱法研究DNA i-motif的折叠与解折叠动力学

陈春1，黎明2,*，杨忠强1，刘冬生

21,* 清华大学化学系，北京市，100084 中科院研究生院，北京市，100190

*Email: liudongsheng@tsinghua.edu.cn, liming@gucas.ac.cn

利用停流-圆二色谱法，本文研究了DNA i-motif的折叠与解折叠动力学。结果表明，DNA i-motif的折叠与解折叠过程具有pH依赖性，并且时间尺度在100毫秒左右。此外，根据定量数据所构建的模型表明，质子的协同作用对于折叠与解折叠过程非常重要。在解折叠过程中，唯一的限速步骤是两个质子（而非全部六个）被中和掉；而在折叠过程中，却是三个质子协同地结合在DNA i-motif上。这些研究结果有助于理解DNA i-motif的折叠与解折叠动力学，并进一步指导分子机器的构建。[1]

关键词：DNA i-motif；kinetics；folding；unfolding

参考文献

[1] Gehring, K.;Leroy, J.L.;Gueron, M.Nature 1993, 363, 561.The Folding and Unfolding Kinetics of DNA i-motif Studied by

Stopped-flow Circular Dichroism 1, M.Li 2,*, Z.Q.Yang1, D.S.Liu1,*

1Department of Chemistry, Tsinghua University, Beijing, 100084

2College of Physical Sciences, Graduate University of Chinese Academy of Sciences, Beijing,100190

Using the stopped-flow circular dichroism(SFCD)technique, we investigate the kinetics of pH-induced folding and unfolding processes of DNA i-motif.It is found that the molecule can fold or unfold at a timescale of 100 ms when the solution pH is changed and that the folding and unfolding rates strongly depend on the solution pH.Based on quantitative data, we propose a model to decipher the folding and unfolding kinetics.Our model suggests that cooperativity of protons is crucial for either folding or unfolding process.In the unfolding pathway, cooperative neutralization of two protons is the only rate-limiting step.In the folding process, there are three protons cooperatively binding to the DNA strand in the rate-limiting step.These results offer in-depth understanding of the folding and unfolding kinetics of the DNA i-motif and may give precise guidance to construct novel nanostructures.