学术报告：Towards structure of overstretched DNA
报告题目：Towards structure of overstretched DNA报告人： Dr. Hui LI
Fachbereich Physik, Universit?t Konstanz, Germany
报告时间：2009年9月23日（周三） 下午 2:00
报告地点： 嘉定学术活动中心307会议室
报告摘要：Single-molecule experiments on long-chain DNA show that the molecule can be overstretched at nearly constant force (~65 pN) to 60% beyond its relaxed contour length, which is called overstretch transition. Although such unique mechanical property of dsDNA has been discovered for more than 15 years, its origin is still under debate. Molecular dynamics (MD) simulations of a short DNA duplex with 12 basepairs suggest that it is caused by a transition to a new conformation (”S-DNA”) with inclined base pairs; competing scenarios based on thermodynamic considerations and steered MD simulations suggest the force plateau to arise from a continuous loss of basepairing under external force. In this presentation the author will show their efforts to the DNA structure at this overstretch transition both in computer simulation and in experiments. Structures of a 30bp DNA from steered MD simulation shows coexistence of “B-DNA like” and “S-DNA like” structure separated by unpaired bases. Surface force apparatus (SFA) experiment is proposed to stretch amount of DNA simultaneously and detect the stretched structure. Force curves measured with optical tweezers and simulated structure of YoYo-1 intercalated DNA will also be discussed.
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