When Ends Meet: Circular DNA Stretches Differently in Elongational Flows
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- 作者：Yanfei Li ; Kai-Wen Hsiao ; Christopher A. Brockman ; Daniel Y. Yates ; Rae M. Robertson-Anderson ; Julia A. Kornfield ; Michael J. San Francisco ; Charles M. Schroeder ; Gregory B. McKenna
- 刊名：Macromolecules
- 出版年：2015
- 出版时间：August 25, 2015
- 年：2015
- 卷：48
- 期：16
- 页码：5997-6001
- 全文大小：336K
- ISSN：1520-5835
文摘
Chain topology has a profound impact on the flow behavior of single macromolecules. For circular polymers, the absence of free ends results in a unique chain architecture compared to linear or branched chains, thereby generating distinct molecular dynamics. Here, we report the direct observation of circular DNA dynamics in transient and steady flows for molecular sizes spanning the range of 25.0鈥?14.8 kilobase pairs (kbp). Our results show that the longest relaxation times of the rings follow a power-law scaling relation with molecular weight that differs from that of linear chains. Also, relative to their linear counterparts, circular DNA molecules show a shifted coil-to-stretch transition and less diverse 鈥渕olecular individualism鈥?behavior as evidenced by their conformational stretching pathways. These results show the impact of chain topology on dynamics and reveal commonalities in the steady state behavior of circular and linear DNA that extends beyond chain architecture.