Purification and characterization of the extracellular laccase produced by Trametes polyzona WR710-1 under solid-state fermentation.

Laccase from Trametes polyzona WR710-1 was produced under solid-state fermentation using the peel from the Tangerine orange (Citrus reticulata Blanco) as substrate, and purified to homogeneity. This laccase was found to be a monomeric protein with a molecular mass of about 71 kDa estimated by SDS-PAGE. The optimum pH was 2.0 for ABTS, 4.0 for L-DOPA, guaiacol, and catechol, and 5.0 for 2,6-DMP. The K(m) value of the enzyme for the substrate ABTS was 0.15 mM, its corresponding V(max) value was 1.84 mM min(-1), and the k(cat)/K(m) value was about 3960 s(-1)  mM(-1). The enzyme activity was stable between pH 6.0 and 8.0, at temperatures of up to 40 °C. The laccase was inhibited by more than 50% in the presence of 20 mM NaCl, by 95% at 5 mM of Fe(2+), and it was completely inhibited by 0.1 mM NaN(3). The N-terminal amino acid sequence of this laccase is AVTPVADLQISNAGISPDTF, which is highly similar to those of laccases from other white-rot basidiomycetes.