To elucidate the chemical interactions underlying the role of metallothioneins (MTs) in reducing the cytotoxicity caused by MeHg(II), we monitored in parallel by electronic absorption and CD spectroscopies the stepwise addition of MeHgCI stock solution to mammalian Zn7-MT1 and the isolated Zn4-αdMT1 and Zn3-βMT1 fragments. The incorporation of MeHg+ into Zn7-MT and Zn 3-βMT entails total displacement of Zn(II) and unfolding of the protein. However, both features are only partial for Zn4-αMT. The different behavior observed for this fragment, whether isolated or constituting one of the two domains of Zn7-MT, indicates interdomain interactions in the whole protein. Overall, the binding properties of Zn 7-MT, Zn4-αMT and Zn3-βMT toward MeHg+ are unprecedented. In addition, the sequestration of MeHg + by Zn7-MT and the concomitant release of Zn(II) are probably two of the main contributions in the detoxifying role of mammalian MT.
|Journal||European Journal of Biochemistry|
|Publication status||Published - 1 Apr 2004|
- Methylmercury(II) binding
- Methylmercury(II) toxicity
- Methylmercury(II)- metallothionein