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H 2 O 2 generation during the auto‐oxidation of coniferyl alcohol drives the oxidase activity of a highly conserved class III peroxidase involved in lignin biosynthesis
Author(s) -
Pomar Federico,
Caballero Nuria,
Pedreño Marı́a A,
Ros Barceló A
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03339-2
Subject(s) - coniferyl alcohol , peroxidase , chemistry , lignin , superoxide dismutase , biochemistry , stereochemistry , enzyme , organic chemistry
Characterization of lignified Zinnia elegans hypocotyls by both alkaline nitrobenzene oxidation and thioacidolysis reveals that coniferyl alcohol units are mainly found as part of 4‐ O ‐linked end groups and aryl‐glycerol‐β‐aryl ether (β‐ O ‐4) structures. Z. elegans hypocotyls also contain a basic peroxidase (EC 1.11.1.7) capable of oxidizing coniferyl alcohol in the absence of H 2 O 2 . Results showed that the oxidase activity of the Z. elegans basic peroxidase is stimulated by superoxide dismutase, and inhibited by catalase and anaerobic conditions. Results also showed that the oxidase activity of this peroxidase is due to an evolutionarily gained optimal adaptation of the enzyme to the μM H 2 O 2 concentrations generated during the auto‐oxidation of coniferyl alcohol, the stoichiometry of the chemical reaction (mol coniferyl alcohol auto‐oxidized/mol H 2 O 2 formed) being 0.496. These results therefore suggest that the H 2 O 2 generated during the auto‐oxidation of coniferyl alcohol is the main factor that drives the unusual oxidase activity of this highly conserved lignin‐synthesizing class III peroxidase.