Haem peroxidases catalyse the H2O2-dependent oxidation of a variety of, usually organic, substrates. Mechanistically, these enzymes are very well characterized: they share a common catalytic cycle that involves formation of a two-electron oxidized intermediate (Compound I) followed by reduction of Compound I by substrate. The substrate specificity is more diverse, however. Most peroxidases oxidize small organic substrates, but there are prominent exceptions to this and the structural features that control substrate specificity remain poorly defined. APX (ascorbate peroxidase) catalyses the H2O2-dependent oxidation of l-ascorbate and has properties that place it at the interface between the class I (e.g. cytochrome c peroxidase) and classical class III (e.g. horseradish peroxidase) peroxidase enzymes. We present a unified analysis of the catalytic and substrate-binding properties of APX, including the crystal structure of the APX-ascorbate complex. Our results provide new rationalization of the unusual functional features of the related cytochrome c peroxidase enzyme, which has been a benchmark for peroxidase-mediated catalysis for more than 20 years.
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March 2004
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Conference Article|
March 01 2004
Defining substrate specificity and catalytic mechanism in ascorbate peroxidase
Emma L. Raven;
Emma L. Raven
1
*Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K.
1To whom correspondence should be addressed (e-mail [email protected]).
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Latesh Lad;
Latesh Lad
*Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K.
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Katherine H. Sharp;
Katherine H. Sharp
*Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K.
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Martin Mewies;
Martin Mewies
*Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K.
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Peter C. E. Moody
Peter C. E. Moody
†Department of Biochemistry, University of Leicester, University Road, Leicester LE1 7RH, U.K.
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Publisher: Portland Press Ltd
Online ISSN: 1744-1439
Print ISSN: 0067-8694
© 2004 The Biochemical Society
2004
Biochem Soc Symp (2004) 71: 27–38.
Citation
Chris Cooper, Mike Wilson, Victor Darley-Usmar, Emma L. Raven, Latesh Lad, Katherine H. Sharp, Martin Mewies, Peter C. E. Moody; Defining substrate specificity and catalytic mechanism in ascorbate peroxidase. Biochem Soc Symp 1 March 2004; 71 27–38. doi: https://doi.org/10.1042/bss0710027
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