Chelation therapy compounds for mercury poisoning usually contain thiol moieties. To improve upon some of shortcomings of current therapies, the present study was undertaken to better understand the complexation interactions of mercury (II) with cysteine containing peptides. Density functional theory and ab initio calculations have been performed to investigate structural and thermodynamic aspects of the interactions of mercury (II) with these peptids for comparison with experiment.  Peptide-Hg2+ complexes, containing cysteine amino acids, have been studies using the COSMO-RI-ZORA-OPBE/def2-svp level for geometry optimizations followed by COSMO-MP2/6-311G**(cc-pVDZ-PP) single-point energies on Hg2+(Cys�)X complexes where X = 1, 2, 3, and 4 as well as 2:2 complexes. Calculations show a strong 2:1 peptide-Hg2+ complex whereby a sulfur atom from each cysteine interacts with mercury. A second weaker 2:2 complex may be present at higher Hg2+ concentrations. It is found that intermolecular hydrogen-bonding interactions among amino acid groups can significantly stabilize these complexes.

Computational studies of complexes between mercury (II) - cysteine-containing peptides

243rd National Meeting (2012)

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