Thermal-stimulated pressure and current studies of bound water in lysozyme.

The state of bound water in crystalized lysozyme was studied by four techniques: electret thermal depolarization currents, thermal-stimulated pressure, isothermal polization decay, and thermogravimetry. Hydration levels ranged from 0 to 40 mg water/g protein. Desorption of bound water dipoles was found to be the main process responsible for electrical depolarization. Two different binding sites for water were identified with long relaxation times at room temperature (order 10(2)s) and activation energies of 0.34 plus or minus 0.02 eV and 0.55 plus or minus 0.04 eV.