Stimulation of Mn peroxidase activity: A possible role for oxalate in lignin biodegradation

I. Ching Kuan, Ming Tien

Research output: Contribution to journalArticlepeer-review

149 Scopus citations

Abstract

Oxalate is produced by numerous wood-degrading fungi. Our studies here show that the white-rot fungus Phanerochaete chrysosporium produces extracellular oxalate under conditions that induce synthesis of the ligninolytic system. Little or no oxalate was detected in cultures grown under high nutrient nitrogen or carbon. This extracellular oxalate was identified and quantitated by HPLC. Its identity was further substantiated by its decomposition by the enzyme oxalate oxidase. The oxalate content of the extracellular fluid (peaking at 60 μM) paralleled the extracellular activity of the lignin-degrading enzyme, Mn peroxidase. Significantly, we demonstrated that oxalate, at physiological concentrations, substantially stimulated Mn peroxidase-catalyzed phenol red oxidation, presumably by its ability to chelate Mn. Stopped flow studies also indicate that oxalate accelerates the turnover of Mn peroxidase. Furthermore, we discovered that oxalate can support Mn peroxidase-catalyzed oxidations in the absence of exogenous H2O2 and in the presence of dioxygen. These results allow us to propose an important role for oxalate, a ubiquitous compound produced by wood-destroying fungi, in lignin biodegradation.

Original languageEnglish (US)
Pages (from-to)1242-1246
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume90
Issue number4
DOIs
StatePublished - Feb 15 1993

All Science Journal Classification (ASJC) codes

  • General

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