A homodimeric laccase with unique characteristics from the yellow mushroom Cantharellus cibarius

The aim of the present study was to isolate a laccase from fruiting bodies of the yellow mushroom Cantharellus cibarius. The fruiting body extract was subjected to a purification protocol that involved ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel and Con A-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The laccase was unadsorbed on DEAE-cellulose and Affi-gel blue gel and adsorbed on Con A-Sepharose. The laccase was composed of two identical subunits each with a molecular mass of 46 kDa. The laccase exhibited a temperature-dependent rise in activity over the temperature range 20-50 degrees C. When the temperature was raised above 60 degrees C there was a fall in enzyme activity. The enzyme manifested maximal activity at pH 4. At and above pH 6 there was a dramatic reduction in activity. The unique features of this fruiting body laccase compared with previously reported mycelial laccases include homodimeric nature, a distinctive N-terminal sequence, a higher optimal pH, and adsorption on only ConA-Sepharose among the various chromatographic media tested.