tetrakis-L-cysteinyl iron 2- 463.94146728515625 464.3699951171875 51.810001373291015625 51.904735565185546875 A protein modification that effectively converts four L-cysteine residues iron atom to tetrakis-L-cysteinyl iron. C 0 Fe 1 H -4 N 0 O 0 S 0 C 12 Fe 1 H 16 N 4 O 4 S 4 C, C, C, C Cross-link 4. METAL Iron MOD:00145 PSI-MOD natural tetrakis(cysteinato-kappaS)-iron tetrakis-L-cysteinyl iron iron containing modified residue metal or metal cluster coordinated L-cysteine residue