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Abstract

A study of complexing properties of the alpha and the beta domains of human metallothioneins with cadmium and/or zinc was carried out, at pH 8, using differential pulse polarography. This method allows one to distinguish the chemical form of the compounds, free metal ions and complexed with the alpha or the beta domains, as well as to monitor the evolution of different species as a function of the proportion of metal ions to the ligand. The alpha and the beta domains are capable of complexing cadmium and/or zinc, separately or after simultaneous additions of both metal ions, resulting in complexes with a M:alpha and M:beta ratios of 4:1 and 3:1, respectively. In the case of binary mixtures pure complexes are formed, whereas in the case of tertiary mixtures, alpha or beta + [Cd + Zn], mixed cadmium and zinc complexes are found. In the latter, two different experimental conditions can be clearly distinguished: an excess of ligand and when the metal ions are in excess, for which two different and characteristic features of polarograms were obtained. So, several stable forms of cadmium and zinc complexation with the alpha and the beta domains exist, depending on the composition of the solution.

Polarographic results have been compared with those obtained by electrospray ionisation mass spectrometry providing the molecular mass of compounds and hence the stoichiometry of different complexes at different proportions of metal ions to the alpha or the beta, under similar experimental conditions. .

Additional information

Authors: PAOLASINI L, European Synchrotron Radiation Facility, Grenoble (FR);VETTIER C, European Synchrotron Radiation Facility, Grenoble (FR);MANNIX D, EC-JRC, Institute for Transuranium Elements, Karlsruhe (DE);LANDER G.H, EC-JRC, Institute for Transuranium Elements, Karlsruhe (DE);STUNAULT A, XmaS CRG at ESRF Grenoble (FR) and Department of Physics, University of Liverpool (UK);BERNHOEFT N, DÚpartment de Recherche Fondamentale sur la Matiþre CondensÚe, Grenoble (FR);DE BERGEVIN F, Laboratoire de Cristallographie, CNRS, Grenoble (FR);KACZOROWSKI D, W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (PL);CZOPNIK A, W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (PL)
Bibliographic Reference: An article published in: Physical Review Letters. Vol. 86. No.18 (2001) pp.4128-4131
Record Number: 200013734 / Last updated on: 2001-09-18
Category: PUBLICATION
Original language: en
Available languages: en
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