Mechanism of aromatic ring cleavage of a. beta. -biphenylyl ether dimer catalyzed by lignin peroxidase of Phanerochaete chrysosporium
Homogeneous lignin peroxidase (LiP) oxidized 1-(4-methoxyphenyl)-2-)2,6-dimethoxy-4-phenylphenoxy)-1,3-propanediol (I) to yield 1-(4-methoxyphenyl)-1,2,3-propanetriol (II), ..cap alpha..-(4-methoxy-phenyl)-2-oxo-1,3-dioxolane-4-methanol (III), 5-(4-methoxyphenyl)-2-oxo-1,3-dioxolane-4-methanol (IV), 4-oxo-3-phenyl-2-butenoic acid methyl ester (V), 5-hydroxy-4-phenyl-2(5H)-furanone (VI), 4-oxo-3-phenyl-2-pentenedioic acid dimethyl ester (VII), and 5-carbomethoxy-5-hydroxy-4-phenyl-2(5H)-furanone (VIII). Products II-VIII are all derived from the opening of the B aromatic ring of the substrate. Oxidation of I in H/sub 2/ /sup 18/O resulted in 87% and 65% incorporation of /sup 18/O into the carbonyl oxygen of III and IV, respectively. Oxidation of I under /sup 18/O/sub 2/ resulted in the incorporation of two atoms of oxygen into the aldehyde (V). Oxidation of I under either /sup 18/O/sub 2/ or H/sub 2//sup 18/O resulted in the incorporation of three atoms of oxygen into the lactol VI. Finally, oxidation of I under either /sup 18/O/sub 2/ or H/sub 2//sup 18/O indicated that four atoms of oxygen were incorporated into the lactol VIII. These results are explained by a mechanism involving the one-electron oxidation of the B ring of the substrate to an aryl cation radical by the H/sub 2/O/sub 2/ oxidized enzyme. In these oxidative pathways, only the formation of the aryl cation radical is enzyme-catalyzed. Subsequent reactions appear to be nonenzymatic, accounting for the variety of ring-opened products formed.
- Research Organization:
- Oregon Graduate Center, Beaverton (USA)
- DOE Contract Number:
- FG06-86ER13550
- OSTI ID:
- 6769179
- Journal Information:
- Biochemistry; (United States), Vol. 27:13
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AROMATICS
MOLECULAR STRUCTURE
OXIDATION
PEROXIDASES
BIOCHEMISTRY
BIOLOGICAL PATHWAYS
DIMERS
LABELLED COMPOUNDS
LIGNIN
OXYGEN 18
PHANEROCHAETE
WATER
CARBOHYDRATES
CHEMICAL REACTIONS
CHEMISTRY
ENZYMES
EVEN-EVEN NUCLEI
FUNGI
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PLANTS
POLYSACCHARIDES
SACCHARIDES
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques