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Cytochrome bd oxidase from Escherichia coli displays high catalase activity: an additional defense against oxidative stress.

Research paper by Vitaliy B VB Borisov, Elena E Forte, Albert A Davletshin, Daniela D Mastronicola, Paolo P Sarti, Alessandro A Giuffrè

Indexed on: 04 Jun '13Published on: 04 Jun '13Published in: FEBS Letters



Abstract

Cytochrome bd oxygen reductase from Escherichia coli has three hemes, b558, b595 and d. We found that the enzyme, as-prepared or in turnover with O2, rapidly decomposes H2O2 with formation of approximately half a mole of O2 per mole of H2O2. Such catalase activity vanishes upon cytochrome bd reduction, does not compete with the oxygen-reductase activity, is insensitive to NO, CO, antimycin-A and N-ethylmaleimide (NEM), but is inhibited by cyanide (Ki ~2.5μM) and azide. The activity, possibly associated with heme-b595, was also observed in catalase-deficient E. coli cells following cytochrome bd over-expression suggesting a protective role against oxidative stress in vivo.