Solution effects and the order of the helix-coil transition in polyalanine

TL;DR

This study investigates helix-coil transitions in polyalanine using multicanonical simulations, revealing how solvent interactions influence the transition's nature and order in different models.

Contribution

It provides a comparative analysis of helix-coil transitions in polyalanine across different solvent models and the gas phase, highlighting the impact of solvation on transition order.

Findings

Helix-coil transition is a true thermodynamic phase transition in all models.

Protein-solvent interactions weaken the transition.

The transition order depends on the solvation model details.

Abstract

We study helix-coil transitions in an all-atom model of polyalanine. Molecules of up to length 30 residues are investigated by multicanonical simulations. Results from two implicit solvent models are compared with each other and with that from simulations in gas phase. While the helix-coil transition is in all three models a true thermodynamic phase transition, we find that its strength is reduced by the protein-solvent interaction term. The order of the helix-coil transition depends on the details of the solvation term.