selenocystine

Selenocystine is a diselenide formed by two selenocysteine residues linked through a Se–Se bond. It is the selenium analog of cystine, the disulfide dimer of cysteine, and serves as a simple model compound for studying selenium-containing redox chemistry.

Chemically, selenocystine consists of two selenocysteine moieties connected by a Se–Se bond formed from the oxidation of their selenol groups. The Se–Se linkage is generally more redox-active and less stable toward reduction than the sulfur analog, reflecting differences in bond strength and reactivity between diselenides and disulfides.

Occurrence and context, Selenocystine is not a common native metabolite in proteins but can arise under oxidative conditions from selenocysteine-containing peptides or proteins. It is widely used in research as a redox-active proxy to study Se–Se bond chemistry, selenocysteine oxidation, and related aspects of selenium biology.

Preparation and handling, Selenocystine can be prepared by oxidation of two equivalents of selenocysteine or by coupling protected selenocysteine derivatives, typically under controlled conditions. It is sensitive to air and strong reducing environments, requiring careful handling and appropriate protective measures when used in experiments.

Applications, In research, selenocystine serves as a model system to investigate selenium redox behavior, the properties of Se–Se bonds, and the comparative chemistry of selenium versus sulfur in amino acid–derived diselenides. Its study helps illuminate aspects of selenoprotein function and selenium biology.