title: Formation of hydroxylated polybrominated diphenyl ethers from laccase-catalyzed oxidation of bromophenols.
abstract: Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been frequently found in the marine biosphere as emerging organic contaminants. Studies to date have suggested that OH-PBDEs in marine biota are natural products. However, the mechanisms leading to the biogenesis of OH-PBDEs are still far from clear. In this study, using a laccase isolated from Trametes versicolor as the model enzyme, we explored the formation of OH-PBDEs from the laccase-catalyzed oxidation of simple bromophenols (e.g., 2,4-DBP and 2,4,6-TBP). Experiments under ambient conditions clearly showed that OH-PBDEs were produced from 2,4-DBP and 2,4,6-TBP in presence of laccase. Polybrominated compounds 2'-OH-BDE68, 2,2'-diOH-BB80, and 1,3,8-TrBDD were identified as the products from 2,4-DBP, and 2'-OH-BDE121 and 4'-OH-BDE121 from 2,4,6-TBP. The production of OH-PBDEs was likely a result of the coupling of bromophenoxy radicals, generated from the laccase-catalyzed oxidation of 2,4-DBP or 2,4,6-TBP. The transformation of bromophenols by laccase was pH-dependant, and was also influenced by enzymatic activity. In view of the abundance of 2,4-DBP and 2,4,6-TBP and the phylogenetic distribution of laccases in the environment, laccase-catalyzed conversion of bromophenols may be potentially an important route for the natural biosynthesis of OH-PBDEs.
authors: State Key Laboratory of Marine Environmental Science, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China; College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: link@xmu.edu.cn.
authors: Kunde
authors: K
authors: Lin
authors: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors: Shiyang
authors: S
authors: Zhou
authors: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors: Xi
authors: X
authors: Chen
authors: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors: Jiafeng
authors: J
authors: Ding
authors: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors: Xiaoyan
authors: X
authors: Kong
authors: Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
authors: Jay
authors: J
authors: Gan
mesh_terms: D002384:Catalysis; D055768:Halogenated Diphenyl Ethers / Q000032:analysis / Q000737:chemistry*; D006842:Hydrocarbons, Brominated / Q000032:analysis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D042845:Laccase / Q000737:chemistry* / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010802:Phylogeny; D055454:Trametes / Q000201:enzymology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D055768:Halogenated Diphenyl Ethers; D006842:Hydrocarbons, Brominated; D014874:Water Pollutants, Chemical; D042845:Laccase
keywords: Dioxins; Emerging contaminants; Laccase; OH-PBDEs; Persistent organic pollutants