Computational Chemistry Resolves a Key Step in the Detoxification of Toxic Mercury Compounds

Demethylation is a key reaction in global mercury cycling.

The Science

Organomercuric compounds such as methylmercury are highly toxic, often forming in mercury-contaminated environments. However these toxic compounds can be demethylated by a variety of naturally-occurring mercury resistant bacteria. The mechanism of a key step in the demethylation of methylmercury by a lyase enzyme known as MerB has now been revealed. A DOE-funded team led by Oak Ridge National Laboratory, with collaborating scientists at several universities, has applied quantum chemical calculations to x-ray structural data for the MerB enzyme to model the demethylation step. Using computationally demanding density functional calculations, the reaction pathways for this process were elucidated and the portions of the enzyme that play a critical role in the demethylation process were identified. These results provide a foundation for seeking additional mutant versions of the enzyme as part of a strategy for optimizing biological remediation of organomercury contamination in the environment. The research is published in the September issue of the Journal of the American Chemical Society.

Principal Investigator

Jerry M. Parks
Oak Ridge National Laboratory

Co-Principal Investigator

Jeremy C. Smith
Oak Ridge National Laboratory


Parks, J. M., H. Guo, C. Momany, L. Liang, S. M. Miller, A. O. Summers, and J. C. Smith. 2009. “Mechanism of Hg−C Protonolysis in the Organomercurial Lyase MerB,” Journal of the American Chemical Society 131, 13278–85. DOI:10.1021/ja9016123.