To the Mechanism of Horseradish Peroxidase-Mediated Degradation of a Recalcitrant Dye Remazol Brilliant Blue R

Abstract

Thein vitroenzymatic metabolism of a recalcitrant dye Remazol Brilliant Blue R (RBBR) was investigated using horseradish peroxidase (HRP). At optimum pH (4.5), the apparent Michaelis constant (KM) value for the oxidation of RBBR catalyzed by HRP is 14.8 μmol l-1. HRP-mediated conversion of RBBR proceedsviaa conventional peroxidase reaction, by a sequential one-electron oxidation of two molecules of RBBR by the peroxidase Compounds I and II. The oxidation is inhibited by radical trapping agents (nicotinamide adenine dinucleotide reduced (NADH), ascorbate, glutathione). This confirms that the peroxidase-mediated oxidation of RBBR proceedsviaradical mechanism. Gel permeation profile of the RBBR oxidation products shows that the pattern of molecular weight distribution was shifted to the higher molecular weight region indicating formation of RBBR oligomers. In addition to HRP, the RBBR dye is also oxidized by another peroxidase, the mammalian lactoperoxidase.