An extracellular peroxidase was purified by chromatofocusing column chromatography from the growth medium of ligninolytic cultures of the white‐rot fungus Phanerochaete chrysosporium Burds BKM‐1767. The enzyme was electrophoretically pure with an Mr of 45 000–47 000. It contained an easily dissociable heme, and required Mn2+ ions for activity. In the presence of hydrogen peroxide and Mn2+ it oxidized compounds such as vanillylacetone, 2,6‐dimethyloxyphenol, curcumin, syringic acid, guaiacol, syringaldazine, divanillylacetone, and coniferyl alcohol. It did not oxidize veratryl alcohol. In reactions requiring Mn2+ and O2, but not hydrogen peroxide, the enzyme oxidized glutathione, dithiothreitol, and NADPH with production of hydrogen peroxide. The hydrogen peroxide produced could be used as a co‐substrate by ligninases such as those that oxidize veratryl alcohol, or by the peroxidase itself to oxidize lignin model compounds.
3 New spectrophotometric enzyme assays were developed for the study of microbial lignin‐degrading enzymes. The conversion of 2‐methoxy‐3‐phenylbenzoic acid to 2‐hydroxy‐3‐phenylbenzoic acid led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white‐rot fungus Phanerochaete chrysosporium. The conversion of methyl 2‐hydroxy‐3‐phenylbenzoate to 2‐hydroxy‐3‐phenylbenzoic acid allowed the identification of an extracellular, aromatic methyl ester esterase produced by this fungus. The Phanerochaete sp. also excreted an enzyme complex that oxidized 4‐(4‐hydroxy‐3‐methoxyphenyl)‐3‐buten‐2‐one, probably to aliphatic products. All 3 novel enzyme activities were produced together with, and probably comprise a part of, the Phanerochaete ligninolytic enzyme complex. Unlike previously known ligninases, these enzymes did not oxidize 3,4‐dimethoxybenzyl alcohol. All 3 were H2O2‐dependent and were activated by Mn2+ ions.
3 New spectrophotometric enzyme assays were developed for the study of microbial lignin‐degrading enzymes. The conversion of 2‐methoxy‐3‐phenylbenzoic acid to 2‐hydroxy‐3‐phenylbenzoic acid led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white‐rot fungus Phanerochaete chrysosporium. The conversion of methyl 2‐hydroxy‐3‐phenylbenzoate to 2‐hydroxy‐3‐phenylbenzoic acid allowed the identification of an extracellular, aromatic methyl ester esterase produced by this fungus. The Phanerochaete sp. also excreted an enzyme complex that oxidized 4‐(4‐hydroxy‐3‐methoxyphenyl)‐3‐buten‐2‐one, probably to aliphatic products. All 3 novel enzyme activities were produced together with, and probably comprise a part of, the Phanerochaete ligninolytic enzyme complex. Unlike previously known ligninases, these enzymes did not oxidize 3,4‐dimethoxybenzyl alcohol. All 3 were H2O2‐dependent and were activated by Mn2+ ions.
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