Phenol oxidation by mushroom waste extracts: a kinetic and thermodynamic study

Tyrosinase activity of mushroom extracts was checked for their ability to degrade phenol. Phenol oxidation kinetics was investigated varying temperature from 10 to 60 C and the initial values of pH, enzyme activity and phenol concentration in the ranges 4.5–8.5, 1.43–9.54 U/mL and 50–600 mg/L, respectively. Thermodynamic parameters of phenol oxidation and tyrosinase reversible inactivation were estimated. Tyrosinase thermostability was also investigated through residual activity tests after extracts exposition at 20–50 C, whose results allowed exploring the thermodynamics of enzyme irreversible thermoinactivation. This study is the first attempt to separate the effects of reversible unfolding and irreversible denaturation of tyrosinase on its activity. Extracts were finally tested on a real oil mill wastewater.