HORSERADISH PEROXIDASE CATALYZED DEGRADATION OF BROMOPHENOL BLUE DYE

Abstract

In this study, the oxidative destruction of bromophenol blue dye with hydrogen peroxide was carried out at pH 4.0-4.1 in the presence of a commercial horseradish peroxidase, as well as peroxidase isolated directly from horseradish roots (Armoracia rusticana). To determine peroxidase activity, a model reaction of the oxidation of phenol to quinone was used. With a dye concentration of 32.7 μM, the optimal concentration of hydrogen peroxide was 0.04 mM at peroxidase concentration of 1.15 nM. The optimal temperature of the enzymatic reaction was determined: at 23 °С for 10 min 90% of the dye was exposed to destruction. When the temperature rises to 50 °С, the reaction rate decreases, and the degree of destruction is 56% for the same time interval. It was shown that the initial rate of peroxidase oxidation of bromophenol blue follows Michaelis-Menten equation. The kinetic parameters of the enzymatic reaction were determined by linearizing Michaelis-Menten equation in Lineweaver-Burk coordinates. It was found that for the peroxidase oxidation reaction of bromophenol blue Michaelis constant and maximum rate were 42.7 μM and 57.5 μM·min^–1, respectively. In this work, а high percentage of dye degradation was also achieved when using peroxidase isolated from horseradish roots. The experiments were conducted at a temperature of 30^оС and pH 4.1. With the increase in the volume of the extract from 0.1 to 0.2 ml, the percentage decolorization increases from 75% to 90%. The results demonstrate the high degradation efficiency of bromophenol blue with the participation of the commercial horseradish peroxidase and peroxidase isolated from horseradish roots. Enzymatic oxidative degradation can be considered as an alternative to biodegradation.