Non-Markovian fluctuations in Markovian models of protein dynamics

TL;DR

This paper develops a theoretical framework explaining non-Markovian conformational fluctuations in proteins as a superposition of Markovian normal mode fluctuations, aligning well with experimental data.

Contribution

It introduces a model where non-Markovian protein fluctuations arise from superimposed Markovian normal modes, supported by Rouse-like dynamics.

Findings

Rouse-like normal mode dynamics fit experimental correlation functions

Non-Markovian fluctuations can be explained by superposition of Markovian modes

Scaling arguments support the theoretical model

Abstract

Recent experiments using fluorescence spectroscopy have been able to probe the dynamics of conformational fluctuations in proteins. The fluctuations are Gaussian but do not decay exponentially, and are therefore, non-Markovian. We present a theory where non-Markovian fluctuation dynamics emerges naturally from the superposition of the Markovian fluctuations of the normal modes of the protein. A Rouse-like dynamics of the normal modes provides very good agreement to the experimentally measured correlation functions. We provide simple scaling arguments rationalising our results.