[Yellow laccase from the fungus Pleurotus ostreatus D1: purification and characterization]

Yellow laccase was isolated from a solid-phase culture of the fungus Pleurotus ostreatus D1 and characterized. It is a copper-containing enzyme with molecular weight 64 kDa. Its absorption spectrum lacks the maximum at 610 nm, characteristic of fungal laccases and corresponding to type I copper atom. The optimum pH values for the enzyme were determined. They proved to be: 7.0 for syringaldazine, 8.0 for pyrocatechol, and 4.0 for 2,2'-azine-bis-(3-ethylbenzothiazoline-6-sulfonate and 2,6-dimethoxyphenol. Kinetic parameters (Km and Vmax) for oxidation of these substrates were determined. The effect of inhibitors (SDS, 2-mercaptoethanol, and EDTA) on the activity of the enzyme was studied. It was shown that yellow laccase from Pleurotus ostreatus D1 oxidized anthracene to anthraquinone by 95% without any mediator.