Open AccessPathways for production of Fenton's reagent by wood‐rotting fungi
Author(s) -
Wood Paul M.
Publication year - 1994
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1994.tb00051.x
Subject(s) - chemistry , radical , reagent , autoxidation , lignin , hydroxyl radical , cellobiose dehydrogenase , cellulose , oxalate , superoxide , hydrogen peroxide , cellobiose , photochemistry , fenton's reagent , organic chemistry , fenton reaction , enzyme , cellulase
Many forms of Fe(II) react with H 2 0 2 to generate hydroxyl radicals (Fenton reaction). There is evidence that hydroxyl radicals are important in brown‐rot, while they can be formed by secondary reactions during lignin breakdown by white‐rot fungi. Their involvement in cellulose breakdown creates a range of oxidized sugars. The two reactants of Fenton's reagent can be generated by Fe(II) autoxidation, or by superoxide in reaction with Fe(III). A rapid autoxidation is not possible for complexes with a high Fe(III)/Fe(II) redox potential. Turning to specific pathways for formation of Fenton's reagent, decomposition of Fe(III)‐oxalate is probably solely a photochemical process. Lignin peroxidases can act indirectly as a source of superoxide, either by reactions that lead to a peroxyradical, or by 1‐electron oxidation of an aliphatic compound creating a strong reductant. Cellobiose dehydrogenase can provide a direct enzymic source for Fenton's reagent (S.M. Kremer and P.M. Wood (1992) Eur. J. Biochem. 208, 807–814). In the experiments as published, hydroxyl radical production was limited by the slow interaction of cellobiose dehydrogenase with O 2 . This limitation can be removed by the presence of an iron complex with an autoxidizable Fe(lI) state. The successful use of Fenton's reagent by a living organism requires a spatial separation between initiating enzyme(s) and the site of production of hydroxyl radicals. The mobility of the extra electron on Fe(II) by intermolecular transfer may be important for achieving this separation.