Recombinant synthesis of mouse Zn 3 - ? and Zn 4 - ? metallothionein 1 domains and characterization of their cadmium(II) binding capacity
- 1 September 1997
- journal article
- research article
- Published by Springer Nature in Cellular and Molecular Life Sciences
- Vol. 53 (8) , 681-688
- https://doi.org/10.1007/s000180050088
Abstract
Genetic engineering, coupled with spectro scopic analyses, has enabled the metal binding proper ties of the α and β subunits of mouse metallothionein 1 (MT) to be characterized. A heterologous expression system in E.coli has led to high yields of their pure zinc-complexed forms. The cadmium(II) binding properties of recombinant Zn4-αMT and Zn3-βMT have been studied by electronic absorption and circular dichroism. The former binds Cd(II) identically to α fragments obtained from mammalian organs, showing that the recombinant polypeptide behaves like the na tive protein. Titration of Zn3-βMT with CdCl2 results in the formation of Cd3-βMT. The addition of excess Cd(II) leads to Cd4-βMT which, with the extra loading of Cd(II), unravels to give rise isodichroically to Cd9-βMT. The effect of cadmium-displaced Zn(II) ions and excess Cd(II) above the full metal occupancy of three has been studied using Chelex-100. The Cd3-βMT species is stable in the presence of this strong metal-chelating agent.Keywords
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