论文标题

杂聚合物线圈透明过渡中的普遍性和身份排序

Universality and identity ordering in heteropolymer coil-globule transition

论文作者

Singh, Thoudam Vilip, Shagolsem, Lenin S.

论文摘要

通过计算机模拟研究了能量多分散链的线圈全球链的线圈多分散链,该模型杂聚合系统是单体物种数量与单体总数一样大。在这项研究中,我们系统地探讨了具有不同功能形式和能量分布方差的后果,而能量分布通常对线圈全球过渡。特别是考虑到高斯(g)和统一分布,$δ$的变化多分散性指数对过渡温度$θ^\ ast $,链中的大小,内部结构和空间组织在球体中的内部结构和空间组织以及折叠的动力学。发现模型杂聚合物的过渡温度低于均聚合物对应物的过渡温度,而$θ^\ ast $随$δ$(G和U)和$θ^\ ast({\ rm U})({\ rm u})<θ^\ ast({\θ^\ ast({\ rm G})$始终如一地增加。我们的研究结果表明,$θ^\ ast $受配对能量分布的最可能值(而不是宽度)的约束。有趣的是,崩溃过渡的性质被证明是通用的,即,当正确缩放(无论功能形式和方差如何)时,所有肿胀曲线都落在主曲线上,并且通过对应物的同性聚合物的相同缩放形式很好地描述了它。但是,在淬火后,对于杂聚合物,从线圈到球的过渡相对较快(G和U系统之间没有显着差异,并且在考虑范围内没有显着的$δ$依赖性)。另一方面,通过平均接触概率量化的内部组织显示出不同的缩放制度。另外,我们基于其身份观察到单体的隔离,这在均匀分布的情况下更为明显。

The coil-globule transition of an energy polydisperse chain, a model heteropolymer system where the number of monomer species is as large as the total number of monomers, is studied by means of computer simulations. In this study, we systematically explore the consequences of having different functional form and variance of the energy distribution on the coil-globule transition in general. In particular, considering Gaussian (G) and uniform (U) distributions, the effect of varying polydispersity index, $δ$, on the transition temperature $θ^\ast$, chain size, internal structure and spatial organization of monomers in the globule, and kinetics of the folding are addressed. It is found that the transition temperature of the model heteropolymer is lower than that of the homopolymer counterpart, and $θ^\ast$ increases with $δ$ (both G and U) and $θ^\ast({\rm U}) < θ^\ast({\rm G})$ consistently. The results of our study suggest that $θ^\ast$ is governed by the most probable value (rather than the width) of the pair-wise energy distribution. Interestingly, the nature of the collapse transition turns out to be universal, i.e., when scaled properly (irrespective of the functional form and variance) all the swelling curves fall on a master curve and it is well described by the same scaling form of the homopolymer counterpart. However, following quenching, the transition from coil to globule is relatively fast for heteropolymer (with no significant difference between G and U systems, and no significant $δ$ dependence within the considered range). On the other hand, internal organization in the collapsed state, quantified through mean contact probability, show distinct scaling regimes. Also we observe segregation of monomers based on their identities which is more pronounced in the case of uniform distribution.

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