Effect of Rice Extract Impurities on Cation Exchange Adsorption of Lysozyme

Human lysozyme and hen egg-white lysozyme have numerous applications due to theirantibacterial, antiviral, and antifungal properties. Currently, hen egg-white lysozyme dominates lowcost applications but the recent high-level expression of human lysozyme in rice could provide aneconomical source of lysozyme if purification costs are comparable. This paper evaluates humanlysozyme and hen egg-white lysozyme adsorption to the cation exchange resin, SP-Sepharose FF,and the effect of rice extract on lysozyme purification. The dynamic binding capacities of humanlysozyme were lower than those of hen egg-white at pH 4.5, 6, and 7.5 with ionic strengths from 0 to100 mM (5-20 mS). Ionic strength and pH had similar effects on the capacities, but human lysozymewas more sensitive to these factors than hen egg-white lysozyme. At pH 4.5 and in the presence ofrice extract, the dynamic binding capacities were reduced 20-30%. Therefore, it appears that thedifferent physico-chemical properties of human lysozyme and hen egg-white lysozyme are the majorcontributors to the inferior binding ability of human lysozyme from rice.