부산대학교 도서관

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 MeHgCl stock solution to mammalian Zn7-MT1 and the isolated Zn4-αMT1 and Zn3-βMT1 fragments. The incorporation of MeHg+ into Zn7-MT and Zn3-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 Zn7-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. [ABSTRACT FROM AUTHOR]