Characterization of enzymatic activity of lysozyme in lysozyme–ovotransferrin complex before and after treatment with trypsin

Abstract The native complex of lysozyme and ovotransferrin was isolated after the separation of egg white proteins using non‐denaturing isoelectric focusing, and mobilization toward the cathode by replacement of the cathodic sodium hydroxide solution with a phosphoric acid solution. The treatment of the lysozyme–ovotransferrin complex with trypsin significantly increased the enzymatic activity of lysozyme. Likewise, an increase in the enzymatic activity of lysozyme was also obtained when a mixture of the purified lysozyme and ovotransferrin was treated with trypsin. The increase in lysozyme enzymatic activity after tryptic treatment of the lysozyme–ovotransferrin complex resulted from the liberation of lysozyme from this complex. This was a consequence of the resistance of lysozyme to tryptic digestion and the digestion of ovotransferrin by trypsin into peptide fragments, which do not bind the lysozyme. The developed methodology could be used for the separation and isolation of other protein complexes and for testing their enzymatic and other activities.