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

• DOI: 10.1016/j.biortech.2012.10.085
• Publication Date: 2012-10-29T20:16:48Z
• Authors: Jing Si; Feng Peng; Baokai Cui
• Keywords: Trametes; 0303 health sciences; 03 medical and health sciences; Metals; Enzyme Stability; Laccase; Color; Alkalies; Wastewater; Coloring Agents; Water Pollutants, Chemical; Water Purification

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 Umg(-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 1.0mM 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 25.0mM, 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.