Peroxyl radicals are potential agents of lignin biodegradation

FEBS Letters

Hammel, Kenneth E¹  Kapich, Alexander N¹  Jensen, Kenneth A¹ 

[1] Institute for Microbial and Biochemical Technology, USDA Forest Products Laboratory, Madison, WI 53705, USA

关键词: White rot;    Wood decay;    Lignin biodegradation;    Manganese peroxidase;    Lipid peroxidation;    Peroxyl radical;   

DOI  :  10.1016/S0014-5793(99)01432-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Past work has shown that the extracellular manganese-dependent peroxidases (MnPs) of ligninolytic fungi degrade the principal non-phenolic structures of lignin when they peroxidize unsaturated fatty acids. This reaction is likely to be relevant to ligninolysis in sound wood, where enzymes cannot penetrate, only if it employs a small, diffusible lipid radical as the proximal oxidant of lignin. Here we show that a non-phenolic β-O-4-linked lignin model dimer was oxidized to products indicative of hydrogen abstraction and electron transfer by three different peroxyl radical-generating systems: (a) MnP/Mn(II)/linoleic acid, (b) arachidonic acid in which peroxidation was initiated by a small amount of H₂O₂/Fe(II), and (c) the thermolysis in air of either 4,4′-azobis(4-cyanovaleric acid) or 2,2′-azobis(2-methylpropionamidine) dihydrochloride. Some quantitative differences in the product distributions were found, but these were attributable to the presence of electron-withdrawing substituents on the peroxyl radicals derived from azo precursors. Our results introduce a new hypothesis: that biogenic peroxyl radicals may be agents of lignin biodegradation.

【 授权许可】

Unknown