Abstract
Genetic engineering, coupled with spectroscopic 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 a fragments obtained from mammalian organs, showing that the recombinant polypeptide behaves like the native protein. Titration of Za3-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.
Original language | English |
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Pages (from-to) | 681-688 |
Journal | Cellular and Molecular Life Sciences |
Volume | 53 |
Issue number | 8 |
DOIs | |
Publication status | Published - 5 Nov 1997 |
Keywords
- Cadmium binding
- Chelex
- Circular dichroism
- E. coli expression
- Metallothionein domains
- Recombinant αMT
- Recombinant βMT
- UV-VIS difference spectra