Aromatic ring cleavage of a non-phenolic beta-O-4 lignin model dimer by laccase of Trametes versicolor in the presence of 1-hydroxybenzotriazole.
The novel cleavage products, 2,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)-1-formyloxypropane (II) and 1-(4-ethoxy-3-methoxyphenyl)-1,2,3-trihydroxypropane-2,3-cyclic carbonate (III) were identified as products of a non-phenolic beta-O-4 lignin model dimer, 1,3-dihydroxy-2-(2,6-dimethoxylphenoxy)-1-(4-ethoxy-3-methoxypheny l)propane (I), by a Trametes versicolor laccase in the presence of 1-hydroxybenzotriazole (1-HBT). An isotopic experiment with a 13C-labeled lignin model dimer, 1,3-dihydroxy-2-(2,6-[U-ring-13C] dimethoxyphenoxy)-1-(4-ethoxy-3-methoxyphenyl)propane (I-13C) indicated that the formyl and carbonate carbons of products II and III were derived from the beta-phenoxy group of beta-O-4 lignin model dimer I as aromatic ring cleavage fragments. These results show that the laccase-1-HBT couple could catalyze the aromatic ring cleavage of non-phenolic beta-O-4 lignin model dimer in addition to the beta-ether cleavage, Calpha-Cbeta cleavage, and Calpha-oxidation.
Kawai
S
S
Department of Applied Bioorganic Chemistry, Faculty of Agriculture, Gifu University, Japan. skawai@cc.gifu-u.ac.jp
Nakagawa
M
M
Ohashi
H
H
D001487:Basidiomycota / Q000201:enzymology*; D019281:Dimerization; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D042845:Laccase; D008031:Lignin / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D010088:Oxidoreductases / Q000378:metabolism*; D010636:Phenols; D014230:Triazoles
D006841:Hydrocarbons, Aromatic; D010636:Phenols; D014230:Triazoles; D008031:Lignin; C011852:1-hydroxybenzotriazole; D010088:Oxidoreductases; D042845:Laccase