Effect of hydrostatic pressure on the crystallization of lysozyme based on in situ observations

Abstract The growth rate ( R ) and solubility ( c s ) of the tetragonal crystals of hen egg-white lysozyme were determined under hydrostatic pressure up to 350 MPa based on the observations through transparent windows. When the pH is 4.6 and the NaCl concentration 3.0% (w / w), c s (in % (w / w)) increases with pressure p (in MPa) at 23°C approximately as c s = 0.78 + 0.0152 p . In contrast to the linearly increasing c s , R decreased non-linearly with pressure, and was practically zero in a wide pressure range from about 100 to 200 MPa. This means that conventional methods of determining the solubility based on the concentration change are difficult to be used under high pressure. This problem can be overcome by combining in situ observations with image analyses.