Characterization and purification of the crude laccase enzyme produced by the marine-derived fungus Trematosphaeria mangrovei

The extracellular laccase produced by the marine-derived fungus Trematosphaeria mangrovei was purified and characterized. The crude enzyme reached its maximal activity at 35°C, pH 4.5, enzyme concentration of 5.429mg protein/reaction mixture and substrate concentration of 40mM ABTS. The enzyme was stable for 60min at 35°C and retained about 80 to 90% of its activity after treatment for 60min at 40°C up to 50°C. And the enzyme activity showed the highest stability after 60min exposure at pH 4.5. Also at pH 4 the enzyme retained about 91.60% of its activity after 60min exposure. Fractional precipitation of the fungal extracellular T. mangrovei laccase enzyme with different methods showed that, the enzyme fraction precipitated at 60% acetone was the most favourable enzyme fraction, exhibited 4.84 purification fold. Purification of laccase on sephadex G-100 column showed that, the fraction number 8 of laccase component was the most active has the highest specific activity (1466.49 U/mg protein) and revealed 6.5 purification fold (purification fold 31.47 compared to the culture filtrate). Native polyacrylamide gel electrophoresis (PAGE) of fraction 8 showed a separated single band similar to that of standard enzyme indicating its purity and homogeneity, and different from that of partial purified enzyme.