Abstract: Lysozyme was purified from duck egg white by ammonium sulfate precipitation, CM-Sepharose chromatography and Superdex-200 gel filtration chromatography. The specific activity, yield and purification fold of lysozyme were 33687.26 U/mg, 28.00% and 109.44, respectively. The molecular weight of lysozyme was estimated as approximately 14.82 kD. The optimal pH and temperature against Micrococcus lysodlekticus were 7.0 and 50 ℃, respectively. The enzyme was stable at temperatures below 50 ℃ and pH 5.0—9.0. The apparent Km determined by Lineweaver-Burk method under the optimum conditions was 0.0864 mg/mL. The activity of lysozyme was inhibited by Mg2+, Mn2+, or Fe2+, and enhanced by Zn2+, Cu2+ or Co2+.

Key words: duck egg white, lysozyme, isolation and purification, characterization