Side chain and backbone ordering in a polypeptide

TL;DR

This study uses multicanonical simulations to investigate the folding behavior of polyglutamic acid, revealing that backbone and side-chain ordering are decoupled, with backbone formation preceding side-chain ordering regardless of environment.

Contribution

It demonstrates the decoupling of backbone and side-chain ordering in a simple polypeptide through computational simulations, highlighting the sequence of folding events.

Findings

Backbone ordering occurs before side-chain ordering.

Decoupling of backbone and side-chain transitions observed.

Orderings are environment-independent in sequence.

Abstract

We report results from multicanonical simulations of polyglutamic acid chains of length of ten residues. For this simple polypeptide we observe a decoupling of backbone and side-chain ordering in the folding process. While the details of the two transitions vary between the peptide in gas phase and in an implicit solvent, our results indicate that, independent of the specific surroundings, upon continuously lowering the temperature side-chain ordering occurs only after the backbone topology is completely formed.