The refolding of the urea-reduced/denatured lysozyme (Lys) by high-performance weak cation exchange chromatography was reported in this paper. With the presence of a fixed concentration of urea of 4.0 mol•L^－1 and ammonium sulphate as salt or displacer having the stabilizing role to the structure of native protein molecules in the mobile phase employed, and when the Lys concentration was 15.0～50.0 mg•mL^－1, the bioactivity recovery by the presented method was higher than that by usual dilution method. The optimization of chromatographic conditions for obtaining the high recoveries of both mass and bioactivity of Lys was investigated in detail. The recoveries of both mass and bioactivity could be raised up to 97.8% and 95.4% respectively, as the Lys concentration in sample solution was 20.0 mg•mL^－1. The advantages of the presented method are simple operation, and high recoveries of both mass and bioactivity of Lys refolding, and thus it may possibly become a common method for many kinds of proteins.

Key words: liquid chromatography, weak-cation exchange chromatography, protein refolding, lysozyme, disulfide bond