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A study of the complexing properties of the alpha and beta metallothionein domains with cadmium and/or zinc was performed, at pH 8, using electrospray ionisation mass spectrometry (ESI-MS). The applied method allows one to determine the molecular mass, and hence, the stoichiometry of compounds at different proportions of metal ions to the alpha and beta domains. The alpha and beta domains are capable of complexing cadmium and/or zinc, separately or after simultaneous or sequential additions of metal ions in the ratios a:M = 1:4 and 13:M = 1:3. In the case of binary mixtures, alpha or beta + Cd or Zn pure complexes are formed: Cd2alpha, Crl4alpha and Cdsalpha, Zn3alpha and Zfi4alpha for the alpha domain and Cd3beta and Crl4beta, Zn3beta for beta domain, whereas in the case of tertiary mixtures alpha or beta + [Cd + Zn], mixed cadmium and zinc complexes prevail: Cd3Zn[1alpha], Cd2Zn[2alpha], Cd1Zn[3alpha] and Cd2Zn[1beta] and Cd1Zn[2beta.] These mixed complexes co-exist with pure cadmium complexes Crl4alpha and Crl4beta and Cd3beta in an excess of metal ions, particularly cadmium. So several stable forms of complexation of cadmium and zinc with the alpha and beta domains exist, depending on the composition of the solution. When one of the cations is added to a solution containing the alpha or beta domain complexed with the other cation, it is incorporated into the molecule resulting in its reorganisation, which is illustrated by changes in the abundance of pure and mixed complexes.

Additional information

Authors: DABRIO M, EC-JRC, Institute for Reference Materials and Measurements, Geel (BE);BORDIN G, EC-JRC, Institute for Reference Materials and Measurements, Geel (BE);ROSA RODRIGUEZ A, EC-JRC, Institute for Reference Materials and Measurements, Geel (BE)
Bibliographic Reference: An article published in: Recent Research Developments in Electroanalytical Chemistry. 2(2000) pp.77-88
Record Number: 200013733 / Last updated on: 2001-09-18
Original language: en
Available languages: en