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Electrochemical behavior of metallothioneins and related molecules. Part II: Lys–Cys–Thr–Cys–Cys–Ala thionein fragment [56–61] MT I in the presence of cadmium and/or zinc
Author(s) -
Muñoz Amalia,
Rodriguez Adela Rosa
Publication year - 1995
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140070714
Subject(s) - chemistry , polarography , cadmium , zinc , metallothionein , electrochemistry , dropping mercury electrode , mercury (programming language) , metal , inorganic chemistry , molecule , peptide , chelation , metal ions in aqueous solution , electrode , stereochemistry , organic chemistry , biochemistry , computer science , programming language
An electrochemical study, using differential pulse polarography (DPP), of a peptide Lys–Cys–Thr–Cys–Cys–Ala Thionein Fragment [56–61] MT I (FT) was performed in order to compare the behavior of metallothioneins and that of this less complex molecule, intrinsic to the metallothionein structure. The influence of different parameters, such as the solution pH and the concentration of metal elements, cadmium and zinc was investigated. Two different electrochemical systems were distinguished: in the first one, the mercury electrode itself is involved in the charge transfer steps; in this case, peaks are attributed to the oxidation of the mercury electrode in the presence of the peptide acting as a chelating agent. The second electrochemical system corresponds to the reduction of metal cations, cadmium and zinc, at a dropping mercury electrode either as free ions or complexed by the peptide. The apparent stability constants for complexes of FT with cadmium, zinc and mercury were estimated. The order of affinity is: K ′ HgFT ≫ K ′ CdFT > K ′ ZnFT . The DPP response can be used for elucidation of the chemical forms of compounds (speciation).