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

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)(x)MT-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.