Conformational transitions in random heteropolymer models

TL;DR

This paper investigates the conformational phase behavior of heteropolymers with two monomer types, using computational simulations to map phase diagrams as functions of temperature and monomer composition.

Contribution

It introduces a systematic analysis of heteropolymer conformations using the PERM algorithm, extending previous models to include phase diagrams of extended and compact states.

Findings

Identified phase coexistence regions for heteropolymer conformations.

Mapped how temperature and monomer fraction influence conformational states.

Demonstrated the effectiveness of PERM in studying heteropolymer phase behavior.

Abstract

We study the conformational properties of heteropolymers containing two types of monomers A and B, modeled as self-avoiding random walks on a regular lattice. Such a model can describe in particular the sequences of hydrophobic and hydrophilic residues in proteins (K.F. Lau and K.A. Dill, Macromolecules {\bf 22}, 3986 (1989)) and polyampholytes with oppositely charged groups (Y. Kantor and M. Kardar, Europhys. Lett.{\bf 28}, 169 (1994)). Treating the sequences of the two types of monomers as quenched random variables, we provide a systematic analysis of possible generalizations of this model. To this end we apply the pruned-enriched Rosenbluth chain-growth algorithm (PERM), which allows us to obtain the phase diagrams of extended and compact states coexistence as function of both the temperature and fraction of A and B monomers along the heteropolymer chain.