Kapri Rajeev
Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar - 140 306, Punjab India.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Oct;86(4 Pt 1):041906. doi: 10.1103/PhysRevE.86.041906. Epub 2012 Oct 9.
We study by using Monte Carlo simulations the hysteresis in unzipping and rezipping of a double stranded DNA (dsDNA) by pulling its strands in opposite directions in the fixed force ensemble. The force is increased at a constant rate from an initial value g(0) to some maximum value g(m) that lies above the phase boundary and then decreased back again to g(0). We observed hysteresis during a complete cycle of unzipping and rezipping. We obtained probability distributions of work performed over a cycle of unzipping and rezipping for various pulling rates. The mean of the distribution is found to be close (the difference being within 10%, except for very fast pulling) to the area of the hysteresis loop. We extract the equilibrium force versus separation isotherm by using the work theorem on repeated nonequilibrium force measurements. Our method is capable of reproducing the equilibrium and the nonequilibrium force-separation isotherms for the spontaneous rezipping of dsDNA.
我们通过蒙特卡罗模拟研究了在固定力系综中沿相反方向拉动双链DNA（dsDNA）的两条链时，dsDNA解链和重新复性过程中的滞后现象。力以恒定速率从初始值g(0)增加到高于相界的某个最大值g(m)，然后再减小回到g(0)。我们在解链和重新复性的完整循环中观察到了滞后现象。我们获得了不同拉动速率下解链和重新复性循环中所做的功的概率分布。发现该分布的平均值与滞后回线的面积接近（除了非常快的拉动情况外，差异在10%以内）。我们通过在重复的非平衡力测量中使用功定理来提取平衡力与分离等温线。我们的方法能够重现dsDNA自发重新复性的平衡和非平衡力-分离等温线。
