Conformational changes of ubiquitin under high pressure conditions: A pressure simulated tempering molecular dynamics study.

Molecular dynamics simulations for the system of ubiquitin were performed with pressure simulated tempering to study pressure-induced conformational changes of ubiquitin. The pressure dependence of ubiquitin was analyzed in a wide range of pressure from atmospheric pressure (0.1 MPa) to 1.0 GPa. The fluctuation of the distance between amino-acid residues and the distribution of a largely fluctuating distance were calculated. The large fluctuation of the L8-E34 distance induced by pressure means that the conformation of ubiquitin changes under high pressure conditions. There were more water molecules near the largely fluctuating region at high pressure than at low pressure. The pressure dependence of interaction energies among ubiquitin and water was also calculated to investigate the role of water for the pressure-induced conformational changes of ubiquitin. The protein-water interaction is important when the conformation of ubiquitin changes at high pressure. © 2017 Wiley Periodicals, Inc.