Department of Physics, Center for Soft Matter Research, New York University, New York, New York 10003, USA.
J Phys Chem B. 2011 Dec 8;115(48):14127-35. doi: 10.1021/jp204014r. Epub 2011 Jul 22.
We consider DNA translocation through a pore in a planar membrane. The pore is so narrow that only one DNA segment can fit in. Assuming that the biasing force f acts inside the pore only, and that the DNA monomer number N is asymptotically large, we modify the previously developed treatment of the stretched part of the pre-translocated polymer by introducing the concept of "iso-flux trumpet". We show that friction of a moving chain in the trumpet, although it determines the speed of the process, provides only a marginal fraction of overall dissipation in the process. The dominant dissipation turns out to be due to irreversible entropic squeezing of the chain into the small pore. We also discover that because of the role of the membrane a much larger amount of heat of order k(B)T per monomer gets transferred from the heat bath on the post-translocation side to that on the pre-translocation side.
我们研究 DNA 通过平面膜上的小孔的传输。由于孔非常狭窄，以至于只能容纳一个 DNA 片段。假设偏置力 f 仅作用于孔内，并且 DNA 单体数量 N 是渐近大的，我们通过引入“等流喇叭”的概念来修改之前开发的用于预传输聚合物拉伸部分的处理方法。我们表明，在喇叭中移动链的摩擦力虽然决定了过程的速度，但仅提供了过程中总耗散的一小部分。主要的耗散是由于熵不可逆地将链挤压到小孔中。我们还发现，由于膜的作用，每一个单体大约有 k(B)T 的热量从传输后的热浴转移到传输前的热浴。
