EFFECT OF HYDROSTATIC-PRESSURE ON THE CRYSTALLIZATION OF LYSOZYME BASED ON IN-SITU OBSERVATIONS

The growth rate (R) and solubility (c(s)) of the tetragonal crystals o f hen egg-white lysozyme were determined under hydrostatic pressure up to 350 MPa based on the observations through transparent windows. Whe n 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 degrees C approximately as c(s)=0.78+/-0.0152p. In contrast to the linearly increasing c(s), R d ecreased non-linearly with pressure, and was practically zero in a wid e pressure range from about 100 to 200 MPa. This means that convention al methods of determining the solubility based on the concentration ch ange are difficult to be used under high pressure. This problem can be overcome by combining in situ observations with image analyses.