Study of pH-Induced Folding and Unfolding Kinetics of the DNA i-Motif by Stopped-Flow Circular Dichroism

详细信息    查看全文

• 作者：Chun Chen ; Ming Li ; Yongzheng Xing ; Yingmei Li ; Carl-Christian Joedecke ; Juan Jin ; Zhongqiang Yang ; Dongsheng Liu
• 刊名：Langmuir
• 出版年：2012
• 出版时间：December 21, 2012
• 年：2012
• 卷：28
• 期：51
• 页码：17743-17748
• 全文大小：334K
• 年卷期：v.28,no.51(December 21, 2012)
• ISSN：1520-5827

文摘

Using the stopped-flow circular dichroism (SFCD) technique, we investigate the kinetics of the pH-induced folding and unfolding process of the DNA i-motif. The results show that the molecule can fold or unfold on a time scale of 100 ms when the solution pH is changed. It is also found that the folding and unfolding rates strongly depend on the solution pH. On the basis of quantitative data, we propose theoretical models to decipher the folding and unfolding kinetics. Our models suggest that the cooperativity of protons is crucial for both the folding and unfolding process. In the unfolding process, the cooperative neutralization of two protons (out of the total six protons in the i-motif molecule) is the only rate-limiting step. In the folding process, there exists a critical step in which three protons bind cooperatively to the DNA strand. These results offer an in-depth understanding of the folding and unfolding kinetics of the DNA i-motif and may give precise guidance for constructing novel nanodevices based on the DNA i-motif.