Study of zinc metallothionein from rat liver using electrochemical techniques

Studies of the electrochemical characterization for two isoforms of rat liv er zinc metallothionein (MT) have been performed using differential pulse p olarography (DPP) and square-wave voltammetry (SWV). Three different respon ses due to the Zn(II) reduction have been distinguished, probably indicatin g different forms of complexation of zinc with the thionein. The influence of cadmium additions, as well as variation in the pH of the solution have b een investigated. The additions of cadmium provoke alterations to the zinc complexes signals and the formation of cadmium complexes. However, dependin g on the initial concentration of zinc in the molecule, one of the two peak s of the Cd(II) reduction, attributed to two different forms of complexatio n of cadmium-thionein, is prevalent. The stability of the MT in solution wa s checked as a function of time. All experiments were carried out in an ine rt atmosphere inside a glove box, to avoid oxidation of thiol groups of the MTs.