STUDY OF TEMPERATURE-DEPENDENT PHASE TRANSITIONS ON ENZYMATIC ACTIVITY AND STRUCTURE OF LACCASE FROM
The effect of temperature-dependent phase transitions on catalytic activity and active center structure of laccase produced by the Basidiomycetes C. hirsutus 072 has been studied. It has been established using a light scattering method that laccase exists in solution as monomers and aggregated particles in ratio 85 : 15% respectively. This ratio did not change during freezing thawing procedure and further incubation at room temperature. The complex nature of laccase activity dynamics after thawing and reaching ambient temperature has been shown. It was determined that autooxidation of the T1 center did not occur during the increase of temperature from 12 to 20°C. According to spectrophotometric and EPR spectroscopic data the structure of laccase active center including all copper centers of types T1, T2, and T3 is changed during temperature-dependent phase transition.