2-chloro-1-4-dimethoxybenzene and 2-chloro-1-4-benzoquinone

2-Chloro-1,4-dimethoxybenzene (2Cl-1,4-DMB) oxidation by lignin peroxidase (LiP) proceeds via the formation of the 2Cl-1,4-DMB cation radical as indicated by ESR and UV/vis spectroscopy. The products of the LiP-catalyzed oxidation of 2Cl-1,4-DMB were identified as 2-chloro-1,4-benzoquinone and the dimers dichlorotetramethoxybiphenyl and chloro(chlorodimethoxyphenyl)benzoquinone. The addition of anisyl alcohol (AA) rapidly quenched the 2Cl-1,4-DMB cation radical optical absorption bands, suggesting that the cation radical directly mediates the oxidation of AA. When LiP reactions are conducted in the presence of 50 microM 2Cl-1,4-DMB, the enzyme is inactivated; however, this inactivation can be prevented by the addition of AA. This also suggests that the 2Cl-1,4-DMB cation radical formed in the reaction, in turn, oxidizes AA.

Topics: Anisoles; Benzoquinones; Benzyl Alcohol; Cations; Chlorobenzenes; Coenzymes; Dimerization; Electron Spin Resonance Spectroscopy; Half-Life; Hydrogen Peroxide; Kinetics; Mass Spectrometry; Oxidants; Oxidation-Reduction; Peroxidases; Phanerochaete