Purification and characterisation of laccase from the medicinal wild mushroom Coriolus brevis

Abstract

Laccases are enzymes that catalyse oxidation of various aromatic compounds, with potential industrial and environmental applications. Here, a novel laccase, CbLaccase, was purified to homogeneity from the medicinal wild mushroom Coriolus brevis using standard chromatographic procedures. The overall yield was approximately 11 %. Gel filtration and sodium dodecyl sulphate–polyacrylamide gel electrophoresis revealed that CbLaccase is a monomer with a molecular mass of 51 kDa. The optimal reaction pH with 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) as a substrate was low (pH 2.5), and the optimal reaction temperature was relatively high (70 °C). The enzyme exhibited very low Km (0.02 mM) and high catalytic efficiency (7.2 × 106) with syringaldazine, and its substrate specificity followed the order: syringaldazine > o-dianisidine > 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) > 2,6-dimethoxyphenol > catechol. Addition of 1 mM Cu2+ enhanced the enzymatic activity, whereas dithiothreitol, sodium azide, and diethyldithiocarbamic acid significantly inhibited it. The enzyme was highly stable at high temperatures, over a wide range of pH values, and in the presence of various detergents. These findings suggest that CbLaccase is distinct from laccases previously purified from other sources and may be useful for the degradation of environmental pollutants. © 2024 Elsevier Ltd