Selenium incorporation into sulphur amino acids and glutathione and the stability of the incorporation products

Abstract The reaction of 75 Se‐sodium selenite with cysteine, cystine and glutathione was studied. Selenodicysteine and selenodiglutathione were obtained as the incorporation products of inorganic selenium. The incorporation of selenium into these organic compounds is greatly affected by pH. The equilibrium constants of the selenodicysteine and selenodiglutathione formation were calculated. The stability of selenodicysteine in a strong acidic solution, in the hydrogen peroxide solution and in the presence of mercaptoethylamine were investigated. The mechanism of the decomposition of the investigated selenium compounds was suggested.