Miyuki Morita

Kinetics of Peroxidase Catalyzed Decoloration of Orange II. with Hydrogen Peroxide

The decoloration rate of Orange II is measured at 20°C and pH 9.0 in the presence of hydrogen peroxide and such peroxidases (POD) as horseradish POD (HRP), POD from soybean (SPO), and arthromyces ramosus POD (ARP). The decoloration rate of Orange II is expressed as pseudo-first order reaction kinetics for all PODS used. The rate constants increase in the following order. SPO < HRP < ARP. Rate constant values for HRP and ARP are much greater than that for percarbonate. The differences in rate constants between PODS can be explained in terms of the different reactivities of POD-interme diates for Orange II.

Effect of Various Factors on Orange II Decoloration Reaction by Horseradish Peroxidase in the Presence of Detergent Enzymes

The effects of four detergent enzymes on the Orange II decoloration reaction by horseradish peroxidase (HRP) were investigated. Stainzyme, Lipex, Celluclean, and Savinase did not affect the decoloration reaction up to a concentration of 0.1% Under weak alkaline to alkaline conditions, the presence of four enzymes did not affect the decoloration reaction, but affected the decoloration reaction under neutral to acidic conditions. The effect of Ca2+ and Mg2+ concentrations on Orange II decoloration reactions in the presence of four enzymes was also investigated. Ca2+ and Mg2+ did not affect the decoloration reaction up to 500 ppm.

Decomposition of Fatty Acid and Detergency Using a System Combining Horseradish Peroxidase and p-Iodophenol

The reactivity and detergency of a horseradish peroxidase reaction system with oleic acid, a non-hydrogen donor used as a soil component, were studied. Under a coexistent system of horseradish peroxidase and p-iodophenol, oleic acid decomposed quickly. In addition, because the coexistence of p-iodophenol provided detergency, a new function of horseradish peroxidase was shown.

Reaction Selectivity on Decoloration of Azo Dyes Catalyzed by Peroxidase

An investigation was conducted into the reaction selectivity of azo dye decoloration by peroxidase (POD). The effects of pH and the addition of p-iodophenol on decoloration rate were investigated using 3 types of dye in single-dye and mixed-dye systems. The addition of p-iodophenol accelerated decoloration. In the mixed-dye system, a pH of 8.0 resulted in the highest decoloration rate. HPLC was used to determine the decoloration rate of individual dyes in the mixed-dye system. The decoloration reaction of Orange I proceeded swiftly, decoloration of Orange II was slowed, and decoloration of Orange G was accelerated. The reaction mechanism in the mixed-dye system is considered to be as follows. Orange I reacts much faster than the other dyes, producing radicals immediately after the reaction commences and then decomposing. Meanwhile, since Orange II has a higher oxidation potential than Orange I, the reaction between Orange II and POD begins after completion of the Orange I reaction. The reaction with Orange G, which has a higher oxidation potential than Orange II, commences even later. Some of the Orange II radicals produced undergo radical reactions with Orange G, transferring electrons to Orange G and reverting to Orange II. As a result, the Orange II reaction is inhibited more than in an Orange II-only system. Conversely, when p-iodophenol was introduced into the mixed-dye system, the reaction selectivity was lost as p-iodophenol radicals reacted simultaneously with all 3 dyes.