Molecular dynamics of a protein surface: Ion-residues interactions

Ran Friedman, Esther Nachliel, Menachem Gutman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Time-resolved measurements indicated that protons could propagate on the surface of a protein or a membrane by a special mechanism that enhanced the shuttle of the proton toward a specific site. It was proposed that a suitable location of residues on the surface contributes to the proton shuttling function. In this study, this notion was further investigated by the use of molecular dynamics simulations, where Na+ and Cl- are the ions understudy, thus avoiding the necessity for quantum mechanical calculations. Molecular dynamics simulations were carried out using as a model a few Na+ and Cl- ions enclosed in a fully hydrated simulation box with a small globular protein (the S6 of the bacterial ribosome). Three independent 10-ns-long simulations indicated that the ions and the protein's surface were in equilibrium, with rapid passage of the ions between the protein's surface and the bulk. However, it was noted that close to some domains the ions extended their duration near the surface, thus suggesting that the local electrostatic potential hindered their diffusion to the bulk. During the time frame in which the ions were detained next to the surface, they could rapidly shuttle between various attractor sites located under the electrostatic umbrella. Statistical analysis of the molecular dynamics and electrostatic potential/entropy consideration indicated that the detainment state is an energetic compromise between attractive forces and entropy of dilution. The similarity between the motion of free ions next to a protein and the proton transfer on the protein's surface are discussed.

Original languageEnglish
Pages (from-to)768-781
Number of pages14
JournalBiophysical Journal
Issue number2
StatePublished - Aug 2005


Dive into the research topics of 'Molecular dynamics of a protein surface: Ion-residues interactions'. Together they form a unique fingerprint.

Cite this