L-cysteine residue 0.0 0.0 103.009185791015625 103.15000152587890625 C 3 H 5 N 1 O 1 S 1 2-azanyl-3-sulfanylpropanoic acid alpha-amino-beta-mercaptopropanoic acid Cys L-(+)-cysteine half-cystine (2R)-2-amino-3-sulfanylpropanoic acid C PSI-MOD none 2-amino-3-mercaptopropionic acid MOD:00014 2-amino-3-mercaptopropanoic acid beta-mercaptoalanine natural thioserine alpha-amino-beta-mercaptopropionic acid From DeltaMass: Average Mass: 121. (R)-cysteine Cysteine (C, Cys) L-cysteine 3-mercapto-L-alanine alpha-amino-beta-thiolpropionic acid A protein modification that effectively converts a source amino acid residue to an L-cysteine. modified residue that can arise from different natural residues natural, standard, encoded residue