Physics Department, M. V. Lomonosov Moscow State University, Moscow 119992, Russia.
Phys Rev Lett. 2010 Sep 17;105(12):128302. doi: 10.1103/PhysRevLett.105.128302.
We studied the conformational properties of DNA in a salt solution of the strongly charged protein bovine serum albumin. DNA is compacted when a suitable amount of bovine serum albumin is added to the solution due to a crowding effect and strong electrostatic repulsion between DNA and bovine serum albumin, both of which carry negative charges. However, DNA undergoes an unfolding transition with an increase in the salt concentration. This observation contradicts the current understanding of polymer- and salt-induced condensation, ψ condensation. We propose a simple theoretical model by taking into account the competition between the translational entropy of ions and electrostatic interaction.
我们研究了在带强电荷的牛血清白蛋白盐溶液中 DNA 的构象性质。由于拥挤效应和 DNA 与牛血清白蛋白之间的强静电排斥，当向溶液中加入适量的牛血清白蛋白时，DNA 会被压缩，两者都带负电荷。然而，随着盐浓度的增加，DNA 会经历一个展开的转变。这一观察结果与目前对聚合物和盐诱导凝聚的理解相矛盾，即 ψ 凝聚。我们通过考虑离子的平移熵和静电相互作用之间的竞争，提出了一个简单的理论模型。
