Purification and characterization of lysozyme from filipino venus, Ruditapes philippinarum

Lysozyme from Filipino venus (Ruditapes philippinarum) was purified by ion-exchange and gel filtration chromatography. The purification fold and yield were 3,402 and 32.4%, respectively. The molecular weight was determined to be 13.4 kDa by SDS-PAGE. The specific activity of lysozyme was 3.76×10⁵ units/mg protein with Micrococcus lysodeikticus as a substrate. The optimum temperature and pH of lysozyme were 75°C and 5.5, respectively. Lysozyme activity was decreased with about 45% after heat treatment for 30 min at 80°C, and completely inactivated at 100°C. It was activated by NaCl (10–70 mM), MgCl₂, and CaCl₂ (2–5 mM) whereas it was inhibited by ZnCl₂ (2–30 mM).