Influence of Constraints within a Cyclic Polymer on Solution Properties,Biomacromolecules

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Influence of Constraints within a Cyclic Polymer on Solution Properties
Biomacromolecules ( IF 5.5 ) Pub Date : 2018-01-18 00:00:00 , DOI: 10.1021/acs.biomac.7b01690
Md. D. Hossain ₁ , James C. Reid ₁ , Derong Lu ₁ , Zhongfan Jia ₁ , Debra J. Searles _{1,

2} , Michael J. Monteiro _{1,

2}

Affiliation

Cyclic polymers with internal constraints provide new insight into polymer properties in solution and bulk and can serve as a model system to explain the stability and mobility of cyclic biomacromolecules. The model system used in this work consisted of cyclic polystyrene structures, all with a nearly identical molecular weight, designed with 0–3 constraints located at strategic sites within the cyclic polymer, with either 4 or 6 branch points. The total number of branch points (or arms) within the cyclic ranged from 0 to 18. Molecular dynamic (MD) simulations showed that as the number of arms increased within the cyclic structure, the radius of gyration and the hydrodynamic radius generally decreased, suggesting the greater number of constraints resulted in a more compact polymer chain. The simulations further showed that the excluded volume was much greater for the cyclics compared to a linear polymer at the same molecular weight. The spirocyclic, a structure consisting of three rings joined in series, showed significant excluded volume effects in agreement with experimental data; the reason for which is unclear at this stage. Interestingly, under a size exclusion chromatography flow, the radius of hydration for all the cyclic structures increased compared with the DLS data, and could be explained from the greater swelling of the rings perpendicular to the flow found from previous simulations on rings. This data suggests that the greater compactness, greater excluded volume and structural rearrangements under flow of constrained cyclic polymers could be used to provide a physical basis for understanding greater stability and activity of cyclic biological macromolecules.

中文翻译：

环状聚合物中的约束对溶液性质的影响

具有内部约束的环状聚合物为溶液和本体中的聚合物性质提供了新的见解，并且可以用作解释环状生物大分子的稳定性和迁移性的模型系统。在这项工作中使用的模型系统由环状聚苯乙烯结构组成，所有结构都具有几乎相同的分子量，在环状聚合物内的关键位置处具有0–3个约束条件，具有4个或6个分支点。循环中分支点（或臂）的总数在0到18之间。分子动力学（MD）模拟显示，随着循环结构中臂数的增加，回转半径和流体动力学半径通常会减小，这表明约束的数量越多，聚合物链就越紧密。模拟进一步表明，与相同分子量的线性聚合物相比，环的排除体积要大得多。螺环是由三个环串联而成的结构，与实验数据吻合，表现出明显的排除体积效应。目前尚不清楚其原因。有趣的是，在尺寸排阻色谱分析流程下，与DLS数据相比，所有环状结构的水合半径都增加了，这可以用垂直于环上先前模拟发现的垂直于环的更大的环溶胀来解释。这些数据表明更大的紧凑性，

更新日期：2018-01-18

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