Among the enzymes that wood-rotting polypores secrete, lignin peroxidases (LiPs) have been labeled as the most efficient. Lignin biodegradation has been extensively studied in white-rot fungi, which largely belong to order Polyporales. Without the advent of low molecular weight mediators. These resultsĪre consistent with lignin peroxidase having an exposed active site capable of directly interacting with the lignin polymer In the alternate proposed substrate-binding site completely inhibited the oxidation of the tetrameric model. In contrast, mutation of a Trp residue (W171S) Peroxidase (isozyme H8) in the heme access channel, which is relatively restricted and was previously proposed to be the veratrylĪlcohol-binding site (E146S), had little effect on the oxidation of the tetramer. This indicates that lignin peroxidase is able to attack any of the Cα-Cβ linkages in the tetrameric compound and that the substrate-binding site is well exposed.
All four of these products were also formed from single turnoverĮxperiments. Tetrameric, trimeric, dimeric, and monomeric carbonyl compounds. The four products were identified by mass spectral analyses and compared with synthetic standards. The fungal and recombinant wild type lignin peroxidase both oxidized the tetrameric model forming four products. A nonphenolic tetrameric lignin model was synthesized thatĬontains β-O-4 linkages. Wild type, as well as mutated, recombinant lignin peroxidases. The present study maps the active site of lignin peroxidase in respect to substrate size using either fungal or recombinant
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