Purification of Lysozyme from Protein Mixtures by Solvent-Freeze-Out Technology

The purification of hen egg white lysozyme from a lysozyme/crude extract mixture was carried out by the solvent-freeze-out (SFO) technology on the laboratory scale. Compared to previous works, this investigation focuses on the crystallization of lysozyme from a complicated system. The crystallization conditions were determined by screening tests. Based on these results, the crystallization process was performed in basic buffer solution in which the formation of tetragonal lysozyme crystals is considered to be difficult. The protein composition and purity of the crystals were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzymatic activity was also measured by the use of a spectrophotometer. The results show that lysozyme retained its original enzyme activity.