物理化学学报2017，Vol.33Issue(3)：620-626,7.DOI:10.3866/PKU.WHXB201612011
漆酶催化邻苯二酚开环的自由基反应机制
Radical Mechanism of Laccase-Catalyzed Catechol Ring-Opening
摘要
Abstract
Enzyme-catalyzed reactions are a prominent field of research in green chemistry.Laccase is a multicopper oxidase,which we used to study the oxidation of catechol.A mechanism for this ring-opening reaction is also proposed.A o-benzosemiquinone radical was the initial nascent product of catechol oxidation during the catalytic reaction.This radical underwent two reaction pathways:(1) formation of an intramolecular adduct,which gave a carbon-centered furan-derived radical trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO);(2) formation of an intermolecular adduct producing dimeric and trimeric oligomers,as resolved by mass spectrometry.Products of the furan-like intermediate were also characterized by 1H-NMR.Simultaneously,a hydroxyl radical (·OH) originating from the water solvent was identified by 17O-isotope tracing.The kinetics of this radical were also evident with substrates including 3-and 4-methyl catechol,but not with resorcinol and hydroquinone isomers,3-and 4-nitro catechol,and 2,3-dihydroxynaphthalene.The mechanism of selective activation and ring-opening at the C4-C5 site is discussed.This reaction is distinct from intra-and extra-diol ringcleavages catalyzed by catechol dioxygenase.These results are meaningful for mimicking laccase catalysis to further protein design.关键词
漆酶/自由基氧化/芳香环开环/电子顺磁共振波谱/自旋捕获技术Key words
Laccase/Radical oxidation/Aromatic ring cleavage/Electron paramagnetic resonance spectroscopy/Spin trapping分类
化学化工引用本文复制引用
陈明,王林,谭天,罗学才,郑在,尹若春,苏吉虎,杜江峰..漆酶催化邻苯二酚开环的自由基反应机制[J].物理化学学报,2017,33(3):620-626,7.基金项目
The project was supported by the National Key Basic Research Program of China (973) (2013CB921802),and Fundamental Research Funds for the Central Universities,China,State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources,China (KSL-CUSAb-2012-03).国家重点基础研究发展规划项目(973) (2013CB921802)和亚热带农业生物资源保护与利用国家重点实验室开放课题基金(KSL-CUSAb-2012-03)资助 （973）
