Ascorbic Acid Is a Slowly Oxidizable Substrate of Horseradish Peroxidase

V. V. Rogozhin^1,2 and V. V. Verkhoturov¹

¹Yakutsk State Agricultural Academy, ul. Krasil'nikova 15, Yakutsk, 677018 Russia; fax: (41122) 26-4949.

²To whom correspondence should be addressed.

Submitted July 2, 1997; revision submitted August 19, 1997.

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The steady-state kinetics of ascorbic acid oxidation catalyzed by horseradish peroxidase was studied. Ascorbic acid was shown to be a slowly oxidizable substrate of peroxidase. Values of k_cat and K_m for this substrate were determined at pH values from 4 to 8. High content of ascorbic acid (22-220 µM) activated the enzyme at all values of pH, while substrate excess inhibited the enzyme.

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KEY WORDS: horseradish peroxidase, ascorbic acid.

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