* To whom correspondence should be addressed.
Received January 27, 1998; Revision received March 24, 1998
The steady-state kinetics of horseradish peroxidase-catalyzed oxidation of hydroquinone was studied. Hydroquinone was shown to be a rapidly oxidizable substrate of the peroxidase. Values of kcat and Km for this substrate were determined in the pH range 4-7. The oxidation of hydroquinone and o-dianisidine was distinguished when both were present in the reaction mixture. o-Dianisidine was not oxidized until hydroquinone was completely converted. The rate of hydroquinone oxidation by peroxidase in the presence of o-dianisidine was 3-10 times higher than the rate of its individual oxidation. The activator decreased the Km for hydroquinone oxidation.
KEY WORDS: horseradish peroxidase, hydroquinone, o-dianisidine, potassium ferrocyanide