title: A mechanism for oxygen exchange between ligated oxometalloporphinates and bulk water.
abstract: Oxygen exchange between high-valent metal-oxo complexes and bulk water has been monitored for nonligated model porphyrins (hemin, FeTDCPPS, MnTMPyP) and the axially ligated microperoxidase-8 (MP-8). Exchange extents up to 90% were measured for MP-8 in spite of the presence of an axial histidine ligand and accompanied by the formation of nonlabelled H(2)O(2) from H(2)(18)O(2). These results point to the existence of a mechanism for oxygen exchange between the high-valent iron-oxo complex and the solvent different from the so-called "oxo-hydroxo tautomerism." Regeneration of the primary oxidant, H(2)O(2), and oxygen exchange by axially ligated porphyrins can be explained by a mechanism involving the reversibility of compound I formation.
authors.affiliation: Laboratory of Biochemistry, Wageningen University, The Netherlands. ivonne.rietjens@P450.BC.WAU.NL
authors.forename: J L
authors.initials: JL
authors.lastname: Primus
authors.forename: K
authors.initials: K
authors.lastname: Teunis
authors.forename: D
authors.initials: D
authors.lastname: Mandon
authors.forename: C
authors.initials: C
authors.lastname: Veeger
authors.forename: I M
authors.initials: IM
authors.lastname: Rietjens
mesh_terms: D000627:Aminophenols / Q000378:metabolism; D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D002374:Catalase / Q000378:metabolism; D002384:Catalysis; D017666:Deuterium Oxide / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000378:metabolism; D006427:Hemin / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D007536:Isomerism; D008024:Ligands; D013058:Mass Spectrometry; D008665:Metalloporphyrins / Q000737:chemistry / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism; D012997:Solvents; D014867:Water / Q000378:metabolism*
chemical_list: D000627:Aminophenols; D000814:Aniline Compounds; D008024:Ligands; D008665:Metalloporphyrins; D016877:Oxidants; D011166:Porphyrins; D012997:Solvents; C410341:tetrakis((2,6-dichloro-3-sulfonatophenyl)porphinato)iron(III); D014867:Water; D017665:Hydroxyl Radical; D006639:Histidine; C050950:tetrakis(N-methyl-4-pyridiniumyl)porphine manganese(III) complex; D006427:Hemin; D006861:Hydrogen Peroxide; D010544:Peroxidases; C021799:microperoxidase; D002374:Catalase; D017666:Deuterium Oxide; C026729:4-aminophenol; D010100:Oxygen; C023650:aniline; D004121:Dimethyl Sulfoxide