Conformational properties of complex polymers: rosette versus star-like structures

TL;DR

This study investigates the size and shape of complex polymer structures with loops and branches, revealing how topology influences their anisotropy and conformational properties, relevant for understanding chromatin organization.

Contribution

It provides a theoretical analysis of Gaussian polymer models with loops and branches, estimating gyration radius and asphericity for different topologies using path integration.

Findings

Star-like structures are more anisotropic than rosette structures of the same size.

The conformational properties depend on the number of loops and branches.

The results offer insights into chromatin organization and DNA compactification.

Abstract

Multiple loop formation in polymer macromolecules is an important feature of the chromatin organization and DNA compactification in the nuclei. We analyze the size and shape characteristics of complex polymer structures, containing in general $f_1$ loops (petals) and $f_2$ linear chains (branches). Within the frames of continuous model of Gaussian macromolecule, we apply the path integration method and obtain the estimates for gyration radius $R_g$ and asphericity $\hat{A}$ of typical conformation as functions of parameters $f_1$, $f_2$. In particular, our results qualitatively reveal the extent of anisotropy of star-like topologies as compared to the rosette structures of the same total molecular weight.