Purification, characterization and decolourization ability of Fomes fomentarius laccase produced in solid medium

Laccase produced by Fomes fomentarius grown on wheat bran in solid cultures was purified to electrophoretic homogeneity by ammonium sulfate precipitation, size-exclusion chromatography and anion-exchange chromatography. A single laccase was found having apparent molecular mass of 51 kDa. The N-terminal amino acid sequence was IGPKTDLTIATGDVSPDG and the highest similarity value was found to the laccase from Trametes sp. 420 (94%). The enzyme exhibits a temperature optimum of 60 °C and has a half-life of 66 min at 60 °C. It manifested maximal activity at pH 4 and showed Km, kcat and kcat/Km values of 26 μM, 106 s−1 and 4 × 106 s−1 M−1, respectively, with 2,6-dimethoxyphenol as substrate. The purified laccase was resistant to several metal ions such as Cd2+, Fe2+, Zn2+, Mg2+, Mn2+ and Cu2+. In addition, the enzyme had ability to decolourize the anthraquinone dye Remazol Brilliant Blue R without mediators.