STUDY ON UNFOLDING PROCESSES OF A SMALL PROTEIN BY MOLECULAR DYNAMICS SIMULATIONS UNDER THE COUPLING EFFECT BETWEEN PRESSURE AND TEMPERATURE
压强温度耦合作用下小蛋白去折叠过程的分子动力学模拟

56 independent molecular dynamics (MD) simulations of the B1 domain of protein G (GB1) were performed to the amount of 88.8ns under fourteen temperatures (from 280 to 540 K) and four pressures (1×102, 2×105, 5×105 and 8×105 kPa). The coupling effect between temperature and pressure during GB1 unfolding processes was studied. The stability of α helix and the β strands increased with increasing pressure. The solvent accessible surface area (SASA) and the other structural parameters decreased with increasing pressure in general. The moderate pressures such as 2×105 and 5×105 kPa restrained the unfolding rate of secondary structure of the protein by slowing down the internal motion of GB1, while higher pressures such as 8×105 kPa accelerated its unfolding rate. The cooperative exposing of the hydrophobic core of GB1 to water occurred at 1×102 and 2×105 kPa among the simulations under different temperatures, but the same phenomena did not occur at 5×105 and 8×105 kPa. The results showed that the temperature-induced unfolding process was perturbed obviously by pressure. The simulation results agree with those obtained from recent experiments.