Oxidation of monomethoxylated aromatic compounds by lignin peroxidase: Role of veratryl alcohol in lignin biodegradation

Journal Article · Tue Sep 18 04:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00489a005· OSTI ID:5923448

Valli, K; Wariishi, Hiroyuki; Gold, M H ^[1]

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1. Oregon Graduate Institute of Science and Technology, Beaverton (USA)

Lignin peroxidase (LiP), an extracellular heme enzyme from the lignin-degrading fungus Phanerochaete chrysosporium, catalyzes the H{sub 2}O{sub 2}-dependent oxidation of a variety of nonphenolic lignin model compounds. The oxidation of monomethoxylated lignin model compounds, such as anisyl alcohol (AA), and the role of veratryl alcohol (VA) in LiP reactions were studied. AA oxidation reached a maximum at relatively low H{sub 2}O{sub 2} concentrations, beyond which the extent of the reactions decreased. The presence of VA did not affect AA oxidation at low molar ratios of H{sub 2}O{sub 2} to enzyme; however, at ratios above 100, the presence of VA abolished the decrease in AA oxidation. Addition of stoichiometric amounts of AA to LiP compound II (LiPII) resulted in its reduction to the native enzyme at rates that were significantly faster than the spontaneous rate of reduction, indicating that AA and other monomethoxylated aromatics are directly oxidized by LiP, albeit slowly. Under steady-state conditions in the presence of excess H{sub 2}O{sub 2} and VA, a visible spectrum for LiPII was obtained. In contrast, under steady-state conditions in the presence of AA a visible spectrum was obtained for LiPIII*, a noncovalent complex of LiPIII and H{sub 2}O{sub 2}. These results support a mechanism whereby VA protects the enzyme from inactivation by H{sub 2}O{sub 2}, thus making more enzyme available for the oxidation of recalcitrant substrates, such as AA and probably polymeric lignin. The results do not support a mechanism whereby VA acts as a radical mediator in the LiP oxidation of AA and other monomethoxylated aromatics.

• OSTI ID: 5923448
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:37; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANISYL RADICALS
ARYL RADICALS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIODEGRADATION
CARBOHYDRATES
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ENZYMES
EUMYCOTA
FUNGI
KINETICS
LIGNIN
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEROXIDASES
PHANEROCHAETE
PLANTS
POLYSACCHARIDES
RADICALS
REACTION KINETICS
SACCHARIDES
SPECTRA
STOICHIOMETRY
SUBSTRATES
VISIBLE SPECTRA