modified L-cysteine residue L-cystine (2R,2'R)-3,3'-disulfane-1,2-diylbis(2-aminopropanoic acid) -2.0156500339508056641 -2.0199999809265136719 2-amino-3-(2-amino-2-carboxy-ethyl)disulfanyl-propanoic acid 3,3'-disulfane-1,2-diylbis(2-azanylpropanoic acid) 3,3'-dithiobis(2-aminopropanoic acid) 3,3'-dithiobisalanine 3,3'-dithiodialanine A protein modification that forms L-cystine by forming a disulfide bond that either cross-links two peptidyl L-cysteine residues, or modifies a peptidyl cysteine with a free cysteine. C 0 H -2 N 0 O 0 S 0 Cys2 Cystine ((Cys)2) L-cystine MOD:01626 PSI-MOD This modification occurs naturally in two forms. It exists as a disulfide cross-link of two cysteine residues (MOD:00034), or as a disulfide cross-link of a cysteine residues and a free cysteine (MOD:00765). beta,beta'-diamino-beta,beta'-dicarboxydiethyldisulfide beta,beta'-dithiodialanine bis(alpha-aminopropionic acid)-beta-disulfide bis(beta-amino-beta-carboxyethyl)disulfide dicysteine natural