What is "lanthionine"

n. (context amino acid English) An analogue of cystine consisting of two alanine residues connected by a single sulfur atom

Lanthionine is a nonproteinogenic amino acid with the chemical formula (HOOC-CH(NH)-CH-S-CH-CH(NH)-COOH). As the monosulfide analog of cystine, lanthionine is composed of two alanine residues that are crosslinked on their β-carbon atoms by a thioether linkage. Despite its name, lanthionine does not contain the element lanthanum.