title: Cleaving mercury-alkyl bonds: a functional model for mercury detoxification by MerB.
abstract: The extreme toxicity of organomercury compounds that are found in the environment has focused attention on the mechanisms of action of bacterial remediating enzymes. We describe facile room-temperature protolytic cleavage by a thiol of the Hg-C bond in mercury-alkyl compounds that emulate the structure and function of the organomercurial lyase MerB. Specifically, the tris(2-mercapto-1-t-butylimidazolyl)hydroborato ligand [Tm(Bu(t))], which features three sulfur donors, has been used to synthesize [Tm(Bu(t))]HgR alkyl compounds (R = methyl or ethyl) that react with phenylthiol (PhSH) to yield [Tm(Bu(t))]HgSPh and RH. Although [Tm(Bu(t))]HgR compounds exist as linear two-coordinate complexes in the solid state, 1H nuclear magnetic resonance spectroscopy indicates that the complexes exist in rapid equilibrium with their higher-coordinate [kappa2-Tm(Bu(t))]HgR and [kappa3-Tm(Bu(t))]HgR isomers in solution. Facile access to a higher-coordinate species is proposed to account for the exceptional reactivity of [Tm(Bu(t))]HgR relative to that of other two-coordinate mercury-alkyl compounds.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Melnick
authors.forename: Gerard
authors.initials: G
authors.lastname: Parkin
mesh_terms: D000473:Alkanes / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D001673:Biodegradation, Environmental; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D008024:Ligands; D008190:Lyases / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008767:Methylmercury Compounds / Q000737:chemistry / Q000378:metabolism*; D008956:Models, Chemical; D015394:Molecular Structure; D009941:Organomercury Compounds / Q000737:chemistry / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry; D013696:Temperature
chemical_list: D000473:Alkanes; D001426:Bacterial Proteins; D008024:Ligands; D008767:Methylmercury Compounds; D009941:Organomercury Compounds; D013438:Sulfhydryl Compounds; D013455:Sulfur; D008190:Lyases; C097247:MerB protein, Bacteria; D003545:Cysteine