Transformations of arylpropane lignin model compounds by a lignin peroxidase of the white-rot fungus Phanerochaete chrysosporium

Various lignin model compounds of the O-arylpropane type were oxidized with purified lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium, and oxidation products were identified by gas-chromatography/mass-spectroscopy procedures. Our results are in accord with the theory that lign...

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Veröffentlicht in:Archives of biochemistry and biophysics 1986-10, Vol.250 (1), p.186-196
Hauptverfasser: Huynh, Van-Ba, Paszczyński, Andrzej, Olson, Pat, Crawford, Ronald
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Sprache:eng
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Zusammenfassung:Various lignin model compounds of the O-arylpropane type were oxidized with purified lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium, and oxidation products were identified by gas-chromatography/mass-spectroscopy procedures. Our results are in accord with the theory that lignin peroxidase catalyzes one-electron oxidations of its substrates with formation of cation radicals, and that these radicals undergo degradative reactions that are predictable from a knowledge of cation radical and oxygen chemistry. Cation radicals formed from O-arylpropane model compounds appeared to undergo the following types of degradative transformations: (1) addition of water to ring-centered radicals, followed by proton loss yielding quinones and alcohols; (2) nucleophilic attack by hydroxy functions on propanoid moieties giving cyclic ketals as intermediates which decompose to yield side chain migration products; (3) transfer of the charge of a radical from a ring to the associated alkyl moiety through an ether bond, with loss of a proton from the latter, forming a new carbon-centered radical. The new alkyl-centered radicals apparently were able to abduct dioxygen to form peroxyl radicals which decomposed giving a variety of oxidation products and probably superoxide anion. Specific examples of the above transformations are presented, and their relevance to lignin degradation is discussed.
ISSN:0003-9861
1096-0384
DOI:10.1016/0003-9861(86)90716-2