title: A nuclear magnetic resonance study of axial ligation for the reduced states of chloroperoxidase, cytochrome P-450cam, and porphinatoiron(II) thiolate complexes.
abstract: The reduced forms of cytochrome P-450cam and chloroperoxidase were examined by proton NMR spectroscopy. The pH and temperature dependences of the proton NMR spectra of both ferrous enzymes are reported. A series of alkyl mercaptide complexes of both synthetic and natural-derivative iron(II) porphyrins was also examined. The proton NMR spectra of these complexes facilitated the assignment of resonances due to the axial ligand in the model compounds on the basis of their isotropic shifts and multiplicities. Comparison of model compound data with that for the reduced enzymes supports assignment of the methylene protons for the axial cysteinate of ferrous cytochrome P-450cam and ferrous chloroperoxidase to proton NMR resonances at 279 and 200 ppm (pH 7.0, 298K), respectively. Differences in the active site structure of the two enzymes are further demonstrated by 15N-NMR spectroscopy of the cyanide complexes of the ferric forms.
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City 52242.
authors.forename: G S
authors.initials: GS
authors.lastname: Lukat
authors.forename: H M
authors.initials: HM
authors.lastname: Goff
mesh_terms: D001665:Binding Sites; D019475:Camphor 5-Monooxygenase; D002711:Chloride Peroxidase / Q000378:metabolism*; D003486:Cyanides / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D003904:Mitosporic Fungi / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D003486:Cyanides; D005296:Ferrous Compounds; D011166:Porphyrins; D013438:Sulfhydryl Compounds; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010544:Peroxidases; D002711:Chloride Peroxidase; D019475:Camphor 5-Monooxygenase