Electrochemical methods for quantification and characterization of metallothioneins induced in Mytilus galloprovincialis

The quantification of the purified metallothionein (MT) component, isolated from the digestive gland of cadmium-exposed Mytilus galloprovincialis, is described based on the analysis of Cd(II) and SH-groups content, applying electrochemical methods. Advantages and disadvantages of the Brdika procedure for the determination of the MT content is discussed. The saturation of binding positions of purified MT with Cd²⁺ ions can be directly followed voltammetrically. Irrespective of the MT concentration, the saturation with Cd²⁺ of in vivo induced mussel MT is achieved at a molar ratio of 5. Cd²⁺ ions are rapidly displaced from the Cd-Th complex after the addition of Pb²⁺ ions, which indicates the kinetically labile type of the complex.