The heat and pressure induced unfolding process was compared for 3 model proteins: Sso7d from the thermophilic archaebacterion Sulfolobus solfataricus, Ribonuclease A, and trypsin. The methods of choice were fluorescence and UV absorbance (4th derivative mode) under equilibrium conditions, unfolding kinetics after a sudden change of the equilibrium by a pressure jump, and by molecular dynamics simulation. Protein stability appears to depend strongly on hydro-phobic interactions, such as stacking between aromatic residues and van der Waals interactions. The mechanism of stabilization appea "s to be protein specific, and it is yet too early to draw general conclusions. However, evidence for an energetic equivalency of unfolded states could be found. Furthermore, the dynamics of protein unfolding can be interpreted in terms of the so-ca led "new view". The p-jump technique appears to be promising for further kinetic investigations.
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