heme-bis-L-cysteine 616.17730712890625 616.489990234375 822.1956787109375 822.780029296875 C 34 H 32 N 4 O 4 Fe 1 MOD:00143 biscysteinyl heme C, C BINDING Heme (covalent) Cross-link 2. natural A protein modification that effectively results from forming an adduct between two cysteine residues and the porphyrin compound heme b, (7,12-diethenyl-3,8,13,17-tetramethylporphyrin-2,18-dipropanoato)iron. HemeCys2 none C 40 H 42 N 6 O 6 S 2 Fe 1 2,4-bis[1-(S-cysteinyl)ethyl]protoporphyrin IX (7,12-bis[(1S)-1-([(2R)-2-amino-2-carboxyethyl]sulfanyl)ethyl]-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-bis[2-carboxyethyl]-N21,N22,N23,N24)-ferrate PSI-MOD heme-bis-L-cysteine porphyrin modified residue metal or metal cluster coordinated L-cysteine residue