Synthesis, characterization and structures of methylmercury complexes with selenoamino acids

Four new methylmercury-selenoamino acid complexes were synthesized, including methylmercury-l-selenoglutathionate, methylmercury-d,l- selenopenicillaminate, and two methylmercury-l-selenomethioninate complexes (one via a Hg-Se bonding and the other Hg-N bonding). All the complexes were characterized by NMR (¹H, ¹³C, ⁷⁷Se and ¹⁹⁹Hg), FT-IR and mass spectra. Their molecular structures were established by single crystal X-ray crystallography (for the Hg-N bonding methylmercury-l-selenomethioninate) and by quantum mechanical calculations using Gaussian-03 with the hybrid functional B3LYP/SDD. All four complexes were found to chemically and structurally resemble their sulfur analogues, with a slightly stronger binding affinity of Hg to Se than to S, suggesting chemical and structural mimicry might play a role in methylmercury-selenium antagonism in biological systems.