Novel DyP from the basidiomycete Pleurotus sapidus: substrate screening and kinetics

Abstract A novel Dye-decolorizing peroxidase from the basidiomycete Pleurotus sapidus was screened for dyedecolorizing peroxidase activity with 2,2‘-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid), Remazol Brilliant Blue R and Guaiacol. Additionally, the catalytic efficiency on degrading β-carotene into volatile products, and the catalyst storage stability with three different additives were also studied. The apparent inhibition constant (KS) was 51.7 μM. Optimal reaction rates (Vmax) and affinity constants (Km) towards the reducing substrates were obtained using Michaelis-Menten kinetic theory. The trend in the calculated Km’s was found to be 7.0 mM > 0.524 mM > 0.051 mM for Guaiacol, 2,2‘-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and Remazol Brilliant Blue R. The storage stability of the catalyst was evaluated with 7.0% w/v PEG400, 7.0% w/v PEG1450 and 0.1% w/v Tween®80 at 5°C over a period of 45 days. The study revealed the longest activity conservation with PEG1450, where rDyP had lost 30% of initial activity. The enzyme solution presented similar pH and temperature dependence to known fungal dye-decolorizing peroxidases with most prolific enzymatic activities registered at pH 4.0 and temperatures below 30°C. An interesting property of the catalyst was oxidation observed in the absence of hydrogen peroxide.