Electrochemical behavior of metallothioneins at mercury and carbon electrodes

Abstract

Rabbit Cd, Zn-metallothionein (Cd, ZnMT), synthetically prepared Cd-metallothionein (CdMT), and apometallothionein (apoMT) have been studied at a mercury electrode and at two types of carbon electrode. At the mercury electrode, different metallothioneins can only be distinguished in cases where their contact with the mercury electrode surface is short. With prolonged time, a mercury compound is formed and its peaks prevail over all the original MT peaks. This conclusion is supported by comparison with apoMT voltammetry at mercury and carbon electrodes. At glassy carbon or carbon composite electrodes, apoMT can be distinguished and determined in the presence of MTs. For both MTs studied, the formation of metal-free S groups can be observed with prolonged electrolysis at negative potentials; this process is reversible and after several CV cycles, the original structure is reestablished.