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以三叶草型结(即31结)为例,采用分子动力学(MD)方法,研究打结高分子链在外场力作用下穿越微孔的动力学过程.模拟发现,在拉动打结高分子链的过程中,结的大小呈涨落变化,直至最后散结.定性讨论了结的存在对高分子链穿孔速率的影响.在外场力作用下,打结高分子链平均穿孔时间(τ)与链长(N)满足标度关系τ～Nα,其中标度系数α随外场力f增大而增大.对于短链,外场力越大,平均穿孔时间越短;而对于较长的链,外场力越大,平均穿孔时间反而越长.本文还研究了结在高分子链中所处的位置对平均穿孔时间的影响.结点位置不同,高分子链平均穿孔时间也不同.初始时,结越靠近第一个穿孔原子,其平均穿孔时间就越长.通过这些研究,可对打结高分子链(特别是打结DNA)穿越微孔的微观过程有一定认识,从而加深对生物大分子穿孔行为的理解。
Taking the clover-type knot (ie, 31 knot) as an example, the kinetic process of kinking polymer chains through micropores under external force was studied by molecular dynamics (MD) method. , The size of the junction fluctuated and fluctuated until it was finally scattered.The qualitative analysis of the influence of the junction on the perforation rate of the polymer chain under the action of external force showed that the average perforation time (τ) The length (N) satisfies the scale relation τ ~ Nα, in which the scale coefficient α increases with the increase of the external force f, and for the short chain, the larger the external field force, the shorter the average piercing time. For the longer chain The bigger the force is, the longer the average piercing time is but the longer the average piercing time is.Furthermore, the effect of the position of the junction in the polymer chain on the average piercing time is also studied. Close to the first perforation atom, the longer the average perforation time.Through these studies, we can understand the microscopic process of kinking the polymer chains (especially the knot DNA) through the micro-pores, thus deepening the biopolymer perforation Understanding of behavior.