Demethylation of Methylmercury in Bird, Fish, and Earthworm
- 21 January 2021
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 55 (3), 1527-1534
- https://doi.org/10.1021/acs.est.0c04948
Abstract
Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding to cysteine residues of proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. MeHgCys complexes can be detoxified in vivo, yet how this occurs is unknown. We report that MeHgCys complexes are transformed into selenocysteinate [Hg(Sec)4] complexes in multiple animals from two phyla (a waterbird, freshwater fish, and earthworms) sampled in different geographical areas and contaminated by different Hg sources. In addition, high energy-resolution X-ray absorption spectroscopy (HR-XANES) and chromatography-inductively coupled plasma mass spectrometry of the waterbird liver support the binding of Hg(Sec)4 to selenoprotein P and biomineralization of Hg(Sec)4 to chemically inert nanoparticulate mercury selenide (HgSe). The results provide a foundation for understanding mercury detoxification in higher organisms and suggest that the identified MeHgCys to Hg(Sec)4 demethylation pathway is common in nature.Funding Information
- Agence Nationale de la Recherche (ANR-10-EQPX-27-01, ANR-12-BS06-0008-01)
- Division of Earth Sciences (EAR-1628956, EAR-1629698)
- U.S. Geological Survey
- Institut Universitaire de France
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