Purification and Characterization of Goose Type Lysozyme from Cassowary (Casuarius casuarius) Egg White

Abstract

A novel goose-type lysozyme was purified from egg white of cassowary bird (Casuarius casuarius). The purification step was composed of two fractionation steps: pH treatment steps followed by a cation exchange column chromatography. The molecular mass of the purified enzyme was estimated to be 20.8 kDa by SDS-PAGE. This enzyme was composed of 186 amino acid residues and showed similar amino acid composition to reported goose-type lysozymes. The N-terminal amino acid sequencing from transblotted protein found that this protein had no N-terminal. This enzyme showed either lytic or chitinase activities and had some different properties from those reported for goose lysozyme. The optimum pH and temperature on lytic activity of this lysozyme were pH 5 and 30°C at ionic strength of 0.1, respectively. This lysozyme was stable up to 30°C for lytic activity and the activity was completely abolished at 80°C. The chitinase activity against glycol chitin showed dual optimum pH around 4.5 and 11. The optimum temperature for chitinase activity was at 50°C and the enzyme was stable up to 40°C.