The extracellular laccase of white-rot fungus, Cerrena unicolor, was purified from culture by Sephadex G-25 and ion-exchange chromatography on DEAE-Toyopearl column and immobilized on various supports. Purified laccase showed two times higher activity after desalting process and 3.7 to 13.4 times activity after DEAE chromatography. During immobilizing process, 93.8% protein and 100% of laccase activity were coupled to the supports. Following immobilization, the optimal pH (5.5) for immobilized laccase was slightly shifted wide pH values (from 5.0 to 6.0) in the case of some supports, and decreased more gradually in alkaline region. Both free and immobilized laccases showed the highest activity at 60℃, however, the immobilized enzyme was more resistant to the wide range of temperature (50～80℃). Even at the 90℃, treated glass beads and Supp-1 maintained almost 80% activity. After 10 days of storage at 4℃, the immobilized laccases retained 95～100% of its initial activity. It was also more stable during storage at 4℃. While, after the same storage time only 34% the initial activity was retained by the free enzyme. Immobilized laccase on glass supports was retained 85～90% activity over 20 days storage, while free enzyme almost zero activity. The immobilized laccases which are more stable and temperature resistant than free enzyme, seem to be more useful.
Mendeley出力
