Stochastic dynamics of model proteins on a directed graph

Lorenzo Bongini, Lapo Casetti, Roberto Livi, Antonio Politi, Alessandro Torcini

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A method for reconstructing the potential energy landscape of simple polypeptidic chains is described. We show how to obtain a faithful representation of the energy landscape in terms of a suitable directed graph. Topological and dynamical indicators of the graph are shown to yield an effective estimate of the time scales associated with both folding and equilibration processes. This conclusion is drawn by comparing molecular dynamics simulations at constant temperature with the dynamics on the graph, defined as a temperature-dependent Markov process. The main advantage of the graph representation is that its dynamics can be naturally renormalized by collecting nodes into "hubs" while redefining their connectivity. We show that the dynamical properties at large time scales are preserved by the renormalization procedure. Moreover, we obtain clear indications that the heteropolymers exhibit common topological properties, at variance with the homopolymer, whose peculiar graph structure stems from its spatial homogeneity. In order to distinguish between "fast" and "slow" folders, one has to look at the kinetic properties of the corresponding directed graphs. In particular, we find that the average time needed to the fast folder for reaching its native configuration is two orders of magnitude smaller than its equilibration time while for the bad folder these time scales are comparable.

Original languageEnglish
Article number061925
Number of pages13
JournalPhysical Review. E, Statistical, Nonlinear and Soft Matter Physics
Volume79
Issue number6
DOIs
Publication statusPublished - Jun 2009

Keywords

  • global optimization
  • energy landscapes

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