Amici Giulia, Caraglio Michele, Orlandini Enzo, Micheletti Cristian
SISSA, International School for Advanced Studies, via Bonomea 265, I-34136 Trieste, Italy.
Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
ACS Macro Lett. 2019 Apr 16;8(4):442-446. doi: 10.1021/acsmacrolett.9b00114. Epub 2019 Apr 1.
We examine how channel confinement affects the equilibrium properties of topologically linked ring polymers and, by contrast, of equivalent unlinked rings, too. By performing extensive simulations of semiflexible rings of different chain length, , and channel diameter, , we discover three notable properties purely due to linking. First, upon entering the weak confinement regime, the length of the physically linked portion, The, becomes independent of chain length. Next, even when confinement is strong enough to pull apart and segregate unlinked rings, stays much larger than in the highly stretched limit. Finally, at fixed , varies approximately as , and we provide a simple scaling argument for this power-law behavior. These properties, which may hold for different link topologies, can be tested by current experimental setups on DNA rings confined in microchannels. Moreover, they could be relevant for the efficient unlinking of newly replicated bacterial chromosomes.
我们研究了通道限制如何影响拓扑连接的环状聚合物的平衡性质，与之形成对比的是，也研究了等效的非连接环的平衡性质。通过对不同链长(L)和通道直径(D)的半柔性环进行大量模拟，我们发现了三种纯粹由于连接而产生的显著性质。首先，进入弱限制区域后，物理连接部分的长度(L_{th})变得与链长无关。其次，即使限制足够强以至于能拉开并分离非连接环，(L_{th})仍比在高度拉伸极限下大得多。最后，在固定的(D)下，(L_{th})大致随(L)变化，并且我们为这种幂律行为提供了一个简单的标度论证。这些性质可能适用于不同的连接拓扑结构，可以通过当前在微通道中限制的DNA环的实验装置进行测试。此外，它们可能与新复制的细菌染色体的有效解链有关。
