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.

The demand for environmentally friendly fiber processing and cleaning formulations prompted us to study the heat resistance, solvent resistance, pH characteristics, and the activation of peroxidases from various sources. Peroxidase has a broad substrate specificity. In a wide pH range, peroxidase was found to react with various hydrogen donor. The rate of reaction with hydrogen donors were found to be influenced by the oxidation potential of the hydrogen donor. Peroxidases from dif ferent sources were found to exhibit dif ferent stabilities and reaction characteristics. Rice full peroxidase showed excellent resistance towards heat, organic solvent, and hydrogen peroxide. The reaction mechanisms of horseradish peroxidase and rice full peroxidase were studied. Since the peroxidase reaction can be controlled by the reaction conditions, these conditions were proposed to suit the specific application.

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