Sequence-Dependent Effects on the Properties of Semiflexible Biopolymers

TL;DR

This paper uses path integral methods to analyze how sequence-dependent variations in spontaneous curvature and torsion affect the physical properties of semiflexible biopolymers, revealing conditions under which these effects can be simplified or become highly sensitive.

Contribution

It provides an exact analytical framework for understanding the influence of sequence correlations on biopolymer mechanics, including conditions for effective averaging.

Findings

Sequence correlations can be incorporated into a model with effective parameters.

For long polymers, sequence-dependent persistence lengths can be approximated by their mean.

Short or flexible polymers exhibit high sensitivity to local sequence variations.

Abstract

Using path integral technique, we show exactly that for a semiflexible biopolymer in constant extension ensemble, no matter how long the polymer and how large the external force, the effects of short range correlations in the sequence-dependent spontaneous curvatures and torsions can be incorporated into a model with well-defined mean spontaneous curvature and torsion as well as a renormalized persistence length. Moreover, for a long biopolymer with large mean persistence length, the sequence-dependent persistence lengths can be replaced by their mean. However, for a short biopolymer or for a biopolymer with small persistence lengths, inhomogeneity in persistence lengths tends to make physical observables very sensitive to details and therefore less predictable.