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arXiv 1907.08784cond-mat.soft
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局部对称性决定线性链的相位:一个简单的肽自组装模型

Local symmetry determines the phases of linear chains: a simple model for the self-assembly of peptide

Tatjana Skrbic, Trinh X. Hoang, Amos Maritan, Jayanth Banavar, Achille Giacometti

摘要:

我们讨论了生物聚合物的简单模型的框架内的对称性破缺的新阶段的出现之间的关系。我们开始与一个经典的模型链分子的球形珠拴在一起,与空间约束,非连续珠不能重叠,并与成对的吸引力的方阱潜力占疏水效应和促进压实。然后,我们讨论的后果,连续打破虚假的对称性。首先,我们允许连续珠粒的部分互穿。除了标准的高温卷曲相和低温塌陷相之外,这导致一类新的边缘紧凑的基态,其包括使人联想到$α$ -螺旋和$β$ -片的构象,所述构象是球状蛋白质的天然状态的构建块。然后,我们讨论了进一步的对称性破缺的圆柱对称附加侧球的骨干珠沿负正常的链的影响,以模仿在真实的蛋白质中的侧链的存在。这导致在先前获得的边缘致密相内出现新相,并出现更复杂的二级结构组装体。这个新的阶段在\textit{de novo}设计的自组装肽的潜在重要性突出。

英文摘要:

We discuss the relation between the emergence of new phases with broken symmetry within the framework of simple models of biopolymers. We start with a classic model for a chain molecule of spherical beads tethered together, with the steric constraint that non-consecutive beads cannot overlap, and with a pairwise attractive square well potential accounting for the hydrophobic effect and promoting compaction. We then discuss the consequences of the successive breaking of spurious symmetries. First, we allow the partial interpenetration of consecutive beads. In addition to the standard high temperature coil phase and the low temperature collapsed phase, this results in a new class of marginally compact ground states comprising conformations reminiscent of $α$-helices and $β$-sheets, the building blocks of the native states of globular proteins. We then discuss the effect of a further symmetry breaking of the cylindrical symmetry on attaching a side-sphere to the backbone beads along the negative normal of the chain, to mimic the presence of side chains in real proteins. This leads to the emergence of a novel phase within the previously obtained marginally compact phase, with the appearance of more complex secondary structure assemblies. The potential importance of this new phase in the \textit{de novo} design of self-assembled peptides is highlighted.

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