Purification and biochemical characterization of a newly produced yellow laccase from Lentinus squarrosulus MR13

A novel yellow laccase was produced from Lentinus squarrosulus MR13 under solid state fermentation. The yellow laccase was purified by a factor of 12.67-fold by ammonium sulfate precipitation, anion exchange chromatography and gel filtration chromatography to a specific activity of 3,772.86 IU mg^-1. Its molecular mass was determined by SDS-PAGE and found to be 66 kDa. The activity of the enzyme was measured with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) as substrate and found to be stable in a broad range of pH (pH 4-9). The optimum temperature of the enzyme was 40 °C. The enzyme was stable at temperatures between 25 and 55 °C and decreased rapidly when the temperature was above 65 °C. Circular dichroism spectra also supported the temperature stability of the enzyme. The K_m and V_max values of the purified yellow laccase were 0.0714 mM and 0.0091 mM min^-1, respectively.