purification, biochemical characterization and dye decolorization capacity of an alkali-resistant and metal-tolerant laccase from trametes pubescens

extracellular laccase (tplac) from trametes pubescens was purified to homogeneity by a three-step method, which resulted in a high specific activity of 18.543 u mg⁻¹, 16.016-fold greater than that of crude enzyme at the same level. tplac is a monomeric protein that has a molecular mass of 68 kda. the enzyme demonstrated high activity toward 1.0 mm abts at an optimum ph of 5.0 and temperature of 50 °c, and under these conditions, the catalytic efficiency (k_cat/k_m) is 8.34 s⁻¹ μm⁻¹. tplac is highly stable and resistant under alkaline conditions, with ph values ranging from 7.0 to 10.0. interestingly, above 88% of initial enzyme activity was maintained in the presence of metal ions at 25.0 mm, leading to an increase in substrate affinity, which indicated that the laccase is highly metal-tolerant. these unusual properties demonstrated that the new fungal laccase tplac has potentials for the specific industrial or environmental applications.