Publication details

Metallothionein and selenite in Brdička reaction



Year of publication 2019
Type Article in Proceedings
Conference XIX. Workshop of Biophysical Chemists and Electrochemists
MU Faculty or unit

Faculty of Science

Keywords metallothionenin; selenite; Brdička reaction; hydrogen evolution; mercury electrode
Description Metallothionein II (MT II) is a cysteine-rich, low-molecular weight protein with a high affinity to heavy metals; it is a single-polypeptide chain with the molecular weight 6-7 kDa, consisting of 61-68 amino acid residues structured into two domains; alpha-domain with four and beta-domain with three binding sites for bivalent ions. The higher MT concentration in tissues reflects a higher amount of toxic heavy metals, oxidative stress, and DNA damage. The MT II has recently been considered as one of the potential cancer markers. Selenium (Se) pertains to the essential part of the human diet and a low Se level in the diet is generally associated with various diseases (e.g., Kashin–Beck disease). Selenium is incorporated into selenoproteins through selenocysteine having the active selenol group (–SeH). Selenium in the form of amino acids is suitable for any food supplementation and it can be easily absorbed compared to inorganic Se, as is sodium selenite (a potential chemotherapeutic agent). The aim of this research was the study of interaction of MT II and selenite by means of the catalytic reaction of hydrogen evolution at a mercury electrode, known under the name of the Brdička reaction. The Brdička reaction has been widely used for protein analysis, even though its mechanism was not completely elucidated. In addition, the mechanism of Brdička reaction may vary from the case to the case. But what matters is that this reaction is usually performed in a solution of ammonia buffer and Co(NH3)6Cl3 in differential pulse voltammetric mode at mercury or amalgam electrodes. We investigated the electrode processes of MT II (rabbit liver metallothionein) at a mercury electrode in the presence of sodium selenite (Na2SeO3) by using differential pulse voltammetry. The interaction between MT II and Na2SeO3 was analyzed via the hydrogen evolution catalytic peaks Cat2. It was found that with the increasing selenite concentration, cobalt in MT is replaced by selenium. When concentration of Na2SeO3 increases above the MT binding capacity, only selenite ions are responsible for Cat2 signals.

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