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Guo F, Tian Y, Ji S, Min H, Ding W, Yu H, Li Y, Ji L. Environmental biotransformation mechanisms by flavin-dependent monooxygenase: A computational study. Chemosphere 2023; 325:138403. [PMID: 36921778 DOI: 10.1016/j.chemosphere.2023.138403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 03/01/2023] [Accepted: 03/12/2023] [Indexed: 06/18/2023]
Abstract
The enzyme-catalyzed metabolic biotransformation of xenobiotics plays a significant role in toxicology evolution and subsequently environmental health risk assessment. Recent studies noted that the phase I human flavin-dependent monooxygenase (e.g., FMO3) can catalyze xenobiotics into more toxic metabolites. However, details of the metabolic mechanisms are insufficient. To fill the mechanism in the gaps, the systemic density functional theory calculations were performed to elucidate diverse FMO-catalyzed oxidation reactions toward environmental pollutants, including denitrification (e.g., nitrophenol), N-oxidation (e.g., nicotine), desulfurization (e.g., fonofos), and dehalogenation (e.g., pentachlorophenol). Similar to the active center compound 0 of cytochrome P450, FMO mainly catalyzed reactions with the structure of the tricyclic isoalloxazine C-4a-hydroperoxide (FADHOOH). As will be shown, FMO-catalyzed pathways are more favorable with a concerted than stepwise mechanism; Deprotonation is necessary to initiate the oxidation reactions for phenolic substrates; The regioselectivity of nicotine by FMO prefers the N-oxidation other than N-demethylation pathway; Formation of the P-S-O triangle ring is the key step for desulfurization of fonofos by FMO. We envision that these fundamental mechanisms catalyzed by FMO with a computational method can be extended to other xenobiotics of similar structures, which may aid the high-throughput screening and provide theoretical predictions in the future.
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Affiliation(s)
- Fangjie Guo
- Quality and Safety Engineering Institute of Food and Drug, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Yilin Tian
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shujing Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Hao Min
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Wen Ding
- School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Yingqi Li
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, 718 East Haizhou Road, Haining 314400, China
| | - Li Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China; School of Environment Science and Spatial Informatics, China University of Mining and Technology, Daxue Road 1, Xuzhou 221116, China.
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