Purification and biochemical characterization of two isolated laccase isoforms from Agaricus bisporus CU13 and their potency in dye decolorization

Agaricus bisporus CU13 laccase was purified using ammonium sulfate precipitation (40-80%), Sephadex G100, and DEAE Sephadex A50 anion exchange column chromatography, respectively. Two laccase isoenzymes (Laccl & Lacc2) with purification folds of 1.40 and 5.81 respectively, were obtained from DEAE Sephadex A50 column. Optimal temperature and pH were recorded at 55 degrees C and pH 5.0 for both laccase isoenzymes using ABTS as substrate. Laccl was more thermostable than Lacc2 with residual activity of 95, 80 and 6%, while Lacc2 only retained 72,25 and 0.4% of its activity after incubation for 90 min. at 50, 60 and 70 degrees C, respectively. Lacc2 retained about 93 and 86% of the initial activity at pH 9.0 and 7.0, whereas Laccl was stable at pH 7.0 and 5.0 followed by pH 9.0 and retained about 87, 76, and 36% of its activity respectively, after 4 h of incubation. Laccl was activated by 40% in the presence of Cu2+ (10 mM). K-m and V-max values found to be 0394 and 0.158 mu M, and 0.1351 and 0.4755 mu mol min(-1) for Laccl and Lacc2, respectively. The efficiency of both isoenzymes to decolorize Acid blue dye, make the enzyme seems to be a prospective for further biotechnological applications. (C) 2018 Elsevier B.V. All rights reserved.