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Cadmium in metallothioneins

Type of publication Peer-reviewed
Publikationsform Contribution to book (peer-reviewed)
Publication date 2013
Author Freisinger Eva, Vašák M.,
Project A. Structures and properties of plant metallothioneins and related artificial proteins - B. Site specific modifications of larger nucleic acids
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Contribution to book (peer-reviewed)

Book Cadmium: From oxicity to essentiality
Editor , Sigel Astrid; Sigel Helmut
Publisher Springer, Dordrecht
Page(s) 339 - 371
ISBN 978-94-007-5178-1
Title of proceedings Cadmium: From oxicity to essentiality
DOI 10.1007/978-94-007-5179-8_11

Abstract

Metallothioneins (MTs) are low-molecular-mass cysteine-rich proteins with the ability to bind mono- and divalent metal ions with the electron configuration d10 in form of metal-thiolate clusters. MTs are thought, among others, to play a role in the homeostasis of essential Zn(II) and Cu(I) ions. Besides these metal ions also Cd(II) can be bound to certain MTs in vivo, giving rise to the perception that another physiological role of MTs is in the detoxification of heavy metal ions. Substitution of the spectroscopically silent Zn(II) ions inmetalloproteins by Cd(II) proved to be an indispensable tool to probe the Zn(II) sites in vitro. In this review, methods applied in the studies of structural and chemical properties of Cd-MTs are presented. The first section focuses on the physical basis of spectroscopic techniques such as electronic absorption, circular dichroism (CD), magnetic CD, X-ray absorption, and perturbed angular correlation of g-rays spectroscopy, as well as mass spectrometry, and their applications to Cd-MTs from different organisms. The following is devoted to the discussion of metal binding affinities of Cd-MTs, cluster dynamics, the reactivity of bound Cd(II) ions with metal ion chelators and of thiolate ligands with alkylating and oxidizing agents. Finally, a brief summary of the known three-dimensional structures of Cd-MTs, determined almost exclusively by multinuclear NMR techniques, is presented. Besides Cd-MTs, the described methods can also be applied to the study of metal binding sites in other metalloproteins.
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