EFFECTS OF PRESSURE ON THE STRUCTURE OF METMYOGLOBIN - MOLECULAR-DYNAMICS PREDICTIONS FOR PRESSURE UNFOLDING THROUGH A MOLTEN GLOBULE INTERMEDIATE

We investigated the pathway for pressure unfolding of metmyoglobin usi ng molecular dynamics (MD) for a range of pressures (0.1 MPa to 1.2 GP a) and a temperature of 300 K. We find that the unfolding of metmyoglo bin proceeds via a two-step mechanism native --> molten globule interm ediate --> unfolded, where the molten globule forms at 700 MPa. The si mulation describes qualitatively the experimental behavior of metmyogl obin under pressure. We find that unfolding of the alpha-helices follo ws the sequence of migrating hydrogen bonds (i, i + 4) --> (i, i + 2).