Current clinical chelation therapy of mercury poisoning generally uses thiol compounds, including cysteine. The present study is conducted to elucidate the associations of mercury(II) with cysteinyl peptides. The effect of increasing the number of cysteinyl residues in a peptide chain on mercury(II) binding and complex type formations was investigated. Three series of di-, tri-, and tetra-cysteinyl peptides, E[CDG]nCG, E[CEG]nCG, and D[CGD]nCG, where n = 1,2, or 3, were prepared by microwave-assisted solid phase peptide synthesis. Their mercury(II) binding constants were evaluated by isothermal titration calorimetry. Complexes formed in different relative ratios of mercury(II) to cysteinyl peptides were also characterized by LTQ orbitrap mass spectrometry. The results from this study show that tetracysteinyl peptides are effective in binding mercury(II) (Kb > 1010 M) and they bind more than one mercury ion per peptide (Hg2(peptide). They may present more attractive options for mercury chelation therapy or environmental heavy metal remediation.

Elucidation of the associations of mercury(II) with cysteinyl peptides

246th National Meeting (2013)

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