arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2402.12470cond-mat.softcond-mat.stat-mechphysics.bio-phq-bio.BM
收藏

均匀电场拉伸带电半柔性聚合物的场-伸长统计

Field-extension statistics of charged semiflexible polymers stretched with uniform electric fields

Ananya Mondal, Greg Morrison

AI总结:

本文改进平均场模型,通过将带电半柔性聚合物链细分为片段并施加不可伸长性约束,更准确地预测均匀电场下的场-伸长统计及横向涨落,为测序技术提供理论支持。

摘要:

单分子力-伸长实验已经能够定量测量生物分子对外加力的力学响应,从而解释它们在关键生物学功能中的作用。带电聚合物(如DNA)在均匀电场中的电泳拉伸就是这样一个例子,目前被用于测序目的。带电聚合物的场-伸长统计与激光光镊装置不同,因为沿链骨架的张力不均匀,其影响目前仍缺乏充分理解。在本文中,我们修改了一个现有的解析可处理的平均场(MF)方法,以考虑电场中张力的异质性。若直接使用该模型来描述带电聚合物(如DNA)在电场下的拉伸,会导致链的局部过度拉伸,并给出不准确的场-伸长统计。我们改进了这一方法,通过将链细分为更小的片段,同时施加链的不可伸长性约束,来考虑张力的不均匀性。我们发现细分后的MF模型在力-伸长曲线方面与模拟结果表现出更好的一致性。我们还表明,使用各向同性平均场模型会高估张力作用以及电场作用下的纵向涨落。我们通过数值微分场-伸长曲线,修正了对平均伸长中涨落的定量预测。我们还发现,由于该模型具有解析可处理性,细分后的MF模型能够准确预测实验相关量的统计,例如横向涨落。这些场-伸长预测可进一步用于在细分后的MF模型中引入约束效应,并发展对测序技术的全面理解。

英文摘要:

Single-molecule force-extension experiments have allowed quantitative measurements of the mechanical responses of biomolecules to applied forces explaining their roles in key biological functions. Electrophoretic stretching of charged polymers such as DNA in uniform electric fields is one such example, currently, used for sequencing purposes. Field-extension statistics of charged polymers differ from laser optical tweezer setups due to a non-uniform tension along the backbone of the chain, the effects of which remain poorly understood. In this paper, we modify an existing analytically tractable mean-field (MF) approach to account for the heterogeneity in tension for electric fields. Naively using this model for stretching of charged polymers such as DNA under electric fields results in local overstretching of the chain and gives inaccurate field-extension statistics. We improve this approach and account for the inhomogeneity in the tension by subdividing the chain into smaller segments while imposing the inextensibility of the chain. We find that the subdivided MF model shows better agreement with the simulations for the force-extension plots. We also show that using an isotropic mean-field model overestimates the longitudinal fluctuations both for tension forces as well as for fields. We correct the quantitative predictions for the fluctuations in the mean extension by numerically differentiating the field-extension plots. We also find that the subdivided MF model can accurately predict the statistics of experimentally relevant quantities, such as transverse fluctuations, due to the analytical tractability of the model. These field-extension predictions may be further used to introduce confinement effects in the subdivided MF model and develop a comprehensive understanding of sequencing technologies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑