Steady-State Kinetics of Peroxidation of 2-Chloro-10-(3-dimethylaminopropyl)-phenothiazine Catalyzed by Horseradish Peroxidase

V. V. Rogozhin^* and V. V. Verkhoturov

Yakutsk State Agricultural Academy, Yakutsk, 677018 Russia; fax: (4112) 26-4949

^* To whom correspondence should be addressed.

Received October 10, 1997; Revision received December 30, 1997

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The steady-state kinetics of peroxidation of 2-chloro-10-(3-dimethylaminopropyl)-phenothiazine (Aminazine) catalyzed by horseradish peroxidase was studied. Aminazine was shown to be a substrate of peroxidase which is oxidized with a slow rate. The values of the catalytic constant (k_cat) and K_m were measured within the pH range from 4.5 to 7.0. In the presence of Aminazine, there was an increase in the rate of peroxidation of potassium ferrocyanide. Binding of an activator to the peroxidase active center caused an increase in the enzyme affinity for ferrocyanide, although had no effect on the k_cat value within the pH range from 5 to 7.

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KEY WORDS: horseradish peroxidase, 2-chloro-10-(3-dimethylaminopropyl)-phenothiazine, potassium ferrocyanide

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