title: Biomimetic studies of terminal oxidases: trisimidazole picket metalloporphyrins.
abstract: Three biomimetic models for the binuclear Fe/Cu (heme/trisimidazole) active site of terminal oxidases, such as cytochrome c oxidase and related enzymes, have been prepared. Based upon a tetrakis(aminophenyl)porphyrin core, these models possess a single covalently linked imidazole-bearing tail on one side of the porphyrin and three imidazole "pickets" on the opposite side of the porphyrin ring. Three different imidazole picket motifs are characterized in free base, Fe, Zn, Fe/Cu, and Zn/Cu forms. A combination of NMR, EPR, and IR demonstrates that, for the N-methylimidazole systems studied, the distal Cu is bound within the trisimidazole environment in the reduced (Cu(I)) and oxidized (Cu(II)) forms. The imidazole picket substitution pattern and state of metalation have significant influence on the interaction of these compounds with CO. For imidazole picket systems containing NH groups, intramolecular H bonds compete with Cu(I) coordination of the N donors.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA. JPC@stanford.edu
authors.forename: James P
authors.initials: JP
authors.lastname: Collman
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Sunderland
authors.forename: Roman
authors.initials: R
authors.lastname: Boulatov
mesh_terms: D000588:Amines / Q000737:chemistry; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme; D007093:Imidazoles / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000138:chemical synthesis*; D008958:Models, Molecular; D008968:Molecular Conformation; D018716:Molecular Mimicry; D009584:Nitrogen / Q000737:chemistry; D010088:Oxidoreductases; D013055:Spectrophotometry, Infrared; D015032:Zinc / Q000737:chemistry
chemical_list: D000588:Amines; D007093:Imidazoles; D008665:Metalloporphyrins; D006418:Heme; D003300:Copper; D002248:Carbon Monoxide; D007501:Iron; D010088:Oxidoreductases; D015032:Zinc; D009584:Nitrogen