Demethylation of methylmercury in bird, fish, and earthworm

Environmental Science & Technology
By: , and 



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 and chromatography-ICP 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.
Publication type Article
Publication Subtype Journal Article
Title Demethylation of methylmercury in bird, fish, and earthworm
Series title Environmental Science & Technology
DOI 10.1021/acs.est.0c04948
Volume 55
Issue 3
Year Published 2021
Language English
Publisher American Chemical Society
Contributing office(s) Forest and Rangeland Ecosys Science Center, Western Ecological Research Center, WMA - Earth System Processes Division
Description 7 p.
First page 1527
Last page 1534
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