MALDI-TOF-MS and XAS analysis of complexes formed by metallothionein with mercury and/or selenium

Mercury (Hg) is highly toxic while selenium (Se) has been found to antagonize Hg. Both Hg and Se have been found to induce metallothioneins (MTs). In this study, the complexes formed by metallothionein-1 (MT-1) with HgCl2 and/or Na2SeO3 was studied using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and X-ray absorption spectrometry (XAS). MALDI-TOF-MS and XAS indicated the formation of Hg-S bond or Se-S bond when MT-1 reacted with HgCl2 or Na2SeO3, respectively. The bond lengths of Hg-S and coordination number in MT-Hg are 2.41 +/- 0.02 angstrom and 3.10 and in MT-Se are 2.50 +/- 0.03 angstrom and 2.69. A MT-Se-Hg complex was formed when MT-1 reacted with both HgCl2 and Na2SeO3, in which the neighboring atom of Hg is Se, while the neighboring atoms of Se are S and Hg. Our study is an important step towards a better understanding of the interaction of HgCl2 and/or Na2SeO3 with proteins like MT-1.

Automated summary

Selenium can antagonize the toxicity of mercury, and it is found that metallothioneins can form complexes with HgCl2 or Na2SeO3. The study indicates that different bond lengths and coordination numbers are formed when metallothionein reacts with HgCl2 or Na2SeO3.