Abstract
Laccases are important and valuable enzymes with a great potential for biotechnological applications. In this study, two novel laccases, LacHU1 and LacHU2, from Alternaria sp. HU have been purified and characterized. The molecular mass of each isoenzyme was ~66 kDa. LacHU1 laccases was yellow and had no typical blue oxidase spectra and LacHU2 had a blue color and characteristic absorption spectra. The catalytic efficiency of LacHU1 for most substrates was higher than that of LacHU2 laccase. Both isoenzymes effectively oxidize flavonoids. Alternaria sp. laccases were successfully immobilized on magnetic nanoparticles. The thermostability of immobilized laccases increased and optimal pH shifted to more alkaline compared to the free laccases. Potential applications of laccases from Alternaria sp. HU are in the oxidation of flavonoids in cotton or in water treatment processes.