Chemical interactions of mercury species and some transition and noble metals towards metallothionein (Zn7MT-2) evaluated using SEC/ICP-MS, RP-HPLC/ESI-MS and MALDI-TOF-MS

Abstract

The chemical affinities of three submetallomes (“Mn, Co, Ni, Cu, Cd”; “Pd, Pt, Au”; and “Hg, CH₃Hg, C₂H₅Hg-THI”) towards metallothionein-2 (Zn₇MT-2) in a physiological solution environment were evaluated using SEC/ICP-MS together with RP-HPLC/ESI-IT-MS and MALDI-TOF-MS, and followed the order: “Zn²⁺ < Cu²⁺, Cd²⁺ > Ni²⁺ > Mn²⁺, Co²⁺”; “Pd²⁺ > Au³⁺ > Pt²⁺”; and “Hg²⁺ > CH₃Hg⁺ > C₂H₅Hg-THI”. Besides these, the structural change and composition of the CH₃Hg–MT-2 complexes formed during the CH₃Hg⁺ titration process were further investigated using CD spectroscopy, RP-HPLC/ESI-MS and MALDI-TOF-MS, indicating that linear and more hydrophobic (CH₃Hg)_xMT-2 (x = 12, 13, 14, 15, 16, 17, 18, 19 and 20) were formed. This information is important in understanding the interactions of the metals with Zn₇MT-2 and their corresponding biological functions and toxicities.