Interaction of Selenite with Metallothionein
| Autoři | |
|---|---|
| Rok publikování | 2019 |
| Druh | Článek ve sborníku |
| Konference | XXV. International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Some selenium compounds are potent inhibitors of the cell growth with remarkable tumor specificity and their use in attempts to treat cancer has a relatively long history dating back to at least 1912 when selenite was reportedly used to cure a tongue cancer. The function of selenium relates to its role as an antioxidant. It is as a constituent part of glutathione peroxidase important in the detoxification of peroxides, which leads to a reduction in the level of reactive oxygen species in cells and tissues. A remarkable feature of selenium consists of its ability to oxidize thiols under reducing conditions and one mode of action recently suggested is the oxidation of thiol groups of metallothionein. Metallothionein II (MT) is a cytosolic, ubiquitous, low-molecular-weight protein present in various tissues of mammals and non-mammals. A high content of thiol groups (–SH) of MTs can bind mineral micronutrients and xenobiotic heavy metals. In this study, we investigated the electrode processes of MT at a mercury electrode in the presence of sodium selenite (Na2SeO3) by means of the Brdička reaction in the differential pulse voltammetric mode. The interaction between MT and Na2SeO3 were analyzed via the hydrogen evolution catalytic signals 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 (MT cannot bind more Se), only selenite ions can be responsible for Cat2 signals. We have answered the questions: (i) how selenite participates in the Brdička reaction, (ii) which competitive behavior of selenium against cobalt should be expected and (iii) what is the sequence of reaction processes in the modified Brdička reaction. A new interpretation leading to complete description of the mechanism is presented. Our results can be helpful in biochemical and clinical studies involving selenium compounds as potential chemotherapeutics. |