Effects of Mn2+and Oxalate on the Catalatic Activity of Manganese Peroxidase

Autor: Serguei L. Timofeevski, Steven D. Aust
Rok vydání: 1997
Předmět:
Zdroj: Biochemical and Biophysical Research Communications. 239:645-649
ISSN: 0006-291X
DOI: 10.1006/bbrc.1997.7453
Popis: Manganese peroxidase from Phanerochaete chrysosporium is an extracellular heme-containing enzyme known to catalyze the oxidation of Mn 2+ to Mn 3+ in a reaction requiring oxalate or another appropriate manganese chelator. We have found that the enzyme can also catalyze a manganese-dependent disproportionation of hydrogen peroxide when a manganese chelator is not included. The catalatic activity was observed in the pH range from 3.0 to 8.5, and the apparent second-order rate constant for catalatic reaction was about 2 × 10 5 M −1 s −1 at pH 4.5 to 7.0 at 25°C. Oxalate inhibited oxygen production by increasing the apparent K m for Mn 2+ for catalatic activity from micromolar to millimolar levels and facilitating peroxidase activity. Catalase-type function was recovered by excess of Mn 2+ in the presence of oxalate. We propose that catalatic activity may protect the enzyme from inactivation by hydrogen peroxide in an environment where free oxalate may be limited.
Databáze: OpenAIRE
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