Pressure-dependent transition in protein dynamics at about 4 kbar revealed by molecular dynamics simulation

Molecular dynamics simulations of a crystalline protein, Staphylococcal nuclease, over the pressure range 1 bar to 15 kbar reveal a qualitative change in the internal protein motions at approximate to 4 kbar. This change involves the existence of two linear regimes in the mean-square displacement for internal protein motion, < u(2)>(P) with a twofold decrease in the slope for P>4 kbar. The major effect of pressure on the dynamics is a loss, with increasing pressure of large amplitude, collective protein modes below 2 THz effective frequency, accompanied by restriction of large-scale solvent translational motion.