Kinetic evidence for rapid oxidation of (-)-epicatechin by human myeloperoxidase
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, D-04107 Leipzig (Germany)
- Department of Chemistry, Division of Biochemistry, University of Natural Resources and Applied Life Sciences, A-1190 Vienna (Austria)
- Institute for Biochemistry and Molecular Biology I, Heinrich Heine University Duesseldorf, D-40001 Duesseldorf (Germany)
Apocynin has been reported to require dimerization by myeloperoxidase (MPO) to inhibit leukocyte NADPH oxidase. (-)-Epicatechin, a dietary flavan-3-ol, has been identified as a 'prodrug' of apocynin-like metabolites that inhibit endothelial NADPH oxidase activity and elevate the cellular level of nitric oxide. Since (-)-epicatechin has tentatively been identified as substrate of MPO, we studied the one-electron oxidation of (-)-epicatechin by MPO. By using multi-mixing stopped-flow technique, we demonstrate that (-)-epicatechin is one of the most efficient electron donors for heme peroxidases investigated so far. Second order rate constants for the (-)-epicatechin-mediated conversion of MPO-compound I to compound II and compound II to resting enzyme were estimated to be 1.9 x 10{sup 7} and 4.5 x 10{sup 6} M{sup -1} s{sup -1}, respectively (pH 7, 25 deg. C). The data indicate that (-)-epicatechin is capable of undergoing fast MPO-mediated one-electron oxidation.
- OSTI ID:
- 21143757
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 371, Issue 4; Other Information: DOI: 10.1016/j.bbrc.2008.04.139; PII: S0006-291X(08)00852-8; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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