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Methylation of inorganic mercury by methylcobalamin in aquatic systems
Author(s) -
Chen Baowei,
Wang Thanh,
Yin Yongguang,
He Bin,
Jiang Guibin
Publication year - 2007
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.1221
Subject(s) - chemistry , methylcobalamin , electrophile , mercury (programming language) , methylation , aqueous solution , inorganic chemistry , organic chemistry , catalysis , biochemistry , computer science , gene , vitamin b12 , programming language
The methylation of inorganic Hg(II) by methylcobalamin in aquatic systems was studied using high‐performance liquid chromatography coupled with UV‐digestion cold vapor atomic fluorescence spectrometry (HPLC‐UV‐CV AFS). Monomethylmercury (MMC) could be positively identified as the reaction product in the aqueous solution. The salinity and pH of the aquatic system have great effects on the formation of MMC, because they could change the species of the reactants in the solution. From an electrophile reaction point of view, salinity and pH alter the electron density of the methyl donor and the electrophilicity of metal ion in the reaction system. This methylation of inorganic Hg(II) is shown to be possible even in highly saline solutions, which indicates its importance in aquatic environments. Kinetic experiments showed that the methylation reaction was fast and first‐order for Hg(II). The first‐order reaction rate was determined to be 0.00612 and 0.000287 min −1 for pH 5.0 and 1.5, respectively. It is suggested that this methylation could occur in the absence of enzymes, in which Hg(II) acts as an electrophile to attack methylcobalamin with a subsequent transfer of carbanion methyl group to the higher oxidized state of Hg(II). Copyright © 2007 John Wiley & Sons, Ltd.