Structure and Action Mechanism of Ligninolytic Enzymes |
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Authors: | Dominic W S Wong |
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Institution: | (1) Western Regional Research Center, USDA-ARS, 800 Buchanan Street, Albany, CA 94710, USA |
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Abstract: | Lignin is the most abundant renewable source of aromatic polymer in nature, and its decomposition is indispensable for carbon
recycling. It is chemically recalcitrant to breakdown by most organisms because of the complex, heterogeneous structure. The
white-rot fungi produce an array of extracellular oxidative enzymes that synergistically and efficiently degrade lignin. The
major groups of ligninolytic enzymes include lignin peroxidases, manganese peroxidases, versatile peroxidases, and laccases.
The peroxidases are heme-containing enzymes with catalytic cycles that involve the activation by H2O2 and substrate reduction of compound I and compound II intermediates. Lignin peroxidases have the unique ability to catalyze
oxidative cleavage of C–C bonds and ether (C–O–C) bonds in non-phenolic aromatic substrates of high redox potential. Manganese
peroxidases oxidize Mn(II) to Mn(III), which facilitates the degradation of phenolic compounds or, in turn, oxidizes a second
mediator for the breakdown of non-phenolic compounds. Versatile peroxidases are hybrids of lignin peroxidase and manganese
peroxidase with a bifunctional characteristic. Laccases are multi-copper-containing proteins that catalyze the oxidation of
phenolic substrates with concomitant reduction of molecular oxygen to water. This review covers the chemical nature of lignin
substrates and focuses on the biochemical properties, molecular structures, reaction mechanisms, and related structures/functions
of these enzymes.
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or handicap. |
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Keywords: | Lignin peroxidase Manganese peroxidase Versatile peroxidase Laccase Lignin degradation |
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