Guaiacol Peroxidase

Peroxidase activity was assayed by using guaiacol as the substrate by following the method described by Xu et al. (2011). The assay system consisted of 0.1 M phosphate buffer pH 7.0, 30 mM guaiacol, 20 mM H₂O₂, and a suitable aliquot of enzyme in a final volume of 3 ml. The GPX activity was determined spectrophotometrically by measuring the increase in absorbance at 470 nm by the conversion of guaiacol to tetraguaiacol due to its oxidation. The molar extinction coefficient of tetraguaiacol was taken as 26.6 mM^–1cm^–1. One unit of enzyme activity is defined as the formation of 1 μmol product of tetraguaiacol by the enzyme catalyzing the reaction per minute at 30°C.