Department of Physics and Astronomy, Sejong University, Seoul 05006, Korea.
Supercomputing Center, Korea Institute of Science and Technology Information, Daejeon 34141, Korea.
ACS Macro Lett. 2022 Mar 15;11(3):382-386. doi: 10.1021/acsmacrolett.1c00655. Epub 2022 Feb 28.
Overall charged polymers with quenched charge sequences often adopt partially globular structures which result from the interplay between the disorder in charge sequences and thermal fluctuations. Simple energetic considerations show that structures consisting of alike (equal-size-equal-charge) globules are not favorable: the structures are intrinsically heterogeneous. We predict the globule distributions with the lowest energies in the size-charge space. The favorable structures comprise large (undercharged) and a majority of small (overcharged) globules. These distributions build a well characterized compact subset, which suggests some order. We also perform large scale molecular dynamics simulations on random quenched +/- sequences. Simulation results show that, despite disorder, the random charge sequences preferentially visit the predicted low energy structures and the predicted order emerges in the pearl-size distribution. This good agreement validates the simple expression used for the energy. Implications for polyampholytes, polyelectrolytes, and intrinsically disordered proteins are discussed.
总体而言，带有猝灭电荷序列的带电聚合物通常采用部分球状结构，这是由于电荷序列的无序性和热波动之间的相互作用所致。简单的能量考虑表明，由相同（等大小-等电荷）小球组成的结构是不利的：结构本质上是异质的。我们预测在大小-电荷空间中具有最低能量的球蛋白分布。有利的结构包括大（欠电荷）和多数小（过电荷）球蛋白。这些分布构成了一个特征良好的紧凑子集，这表明存在一定的秩序。我们还对随机猝灭 +/- 序列进行了大规模分子动力学模拟。模拟结果表明，尽管存在无序性，但随机电荷序列优先访问预测的低能量结构，并且在珍珠大小分布中出现了预测的有序性。这种良好的一致性验证了用于能量的简单表达式。讨论了对聚两性电解质、聚电解质和固有无序蛋白质的影响。
