A laser Raman spectroscopic study on the interaction of alkylmercury with thiol and sulfur-containing compounds.

The interaction of the methylmercury cation with sulfur compounds in aqueous solution at physiological pH was studied by laser Raman spectroscopy. Metal binding is shown to occur preferentially at the sulfhydryl group of sulfur compounds. Raman frequencies of S-Hg stretching of the one-to-one methylmercury-sulfhydryl or sulfur-containing complexes were observed at approximately 330 cm-1. There was no frequency shift when ligands were exchanged. However, the relative intensity (I S-Hg/I C-Hg) was different. The relative intensities of MeHg-thioglycerol, MeHg-cysteine and MeHg-2-mercaptobenzothiazole were 0.18, 0.43 and 0.62, respectively. Methyl-mercury shifted from combination states of lager relative intensity to ones of smaller relative intensity. These results may cast light on the distribution and excretion mechanisms of methylmercury in the human body.