title: Thiol-containing peptide-hemin complexes as models of cytochrome P-450.
abstract: Nine different synthesized thiol tetra- and penta-peptides containing Cys-Ser, Cys-Thr, Cys-His, Cys-Tyr and Cys-Cys in the N- and C-terminals are proposed as new models of apo-P-450. The peptide-hemin complexes in the oxidized (Fe(III] form in solution were characterized by their optical and EPR spectra and found to show hydroxylation activity like that of P-450 enzymes on acetanilide. Although the EPR properties of the complex containing Cys-His and all complexes in the presence of pyridine were similar to those of P-450, the optical properties of these complexes were not completely similar to those of P-450. Based on these results, the sixth heme coordination site of P-450 was discussed.
mesh_terms: D000083:Acetanilides / Q000378:metabolism; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000031:analogs & derivatives; D006427:Hemin; D006900:Hydroxylation; D008862:Microsomes, Liver / Q000378:metabolism; D010455:Peptides; D051381:Rats; D013438:Sulfhydryl Compounds
chemical_list: D000083:Acetanilides; D010455:Peptides; D013438:Sulfhydryl Compounds; D006418:Heme; D006427:Hemin; D003577:Cytochrome P-450 Enzyme System