title: Dioxygen activation by nonheme iron enzymes with the 2-His-1-carboxylate facial triad that generate high-valent oxoiron oxidants.
abstract: The 2-His-1-carboxylate facial triad is a widely used scaffold to bind the iron center in mononuclear nonheme iron enzymes for activating dioxygen in a variety of oxidative transformations of metabolic significance. Since the 1990s, over a hundred different iron enzymes have been identified to use this platform. This structural motif consists of two histidines and the side chain carboxylate of an aspartate or a glutamate arranged in a facial array that binds iron(II) at the active site. This triad occupies one face of an iron-centered octahedron and makes the opposite face available for the coordination of O2and, in many cases, substrate, allowing the tailoring of the iron-dioxygen chemistry to carry out a plethora of diverse reactions. Activated dioxygen-derived species involved in the enzyme mechanisms include iron(III)-superoxo, iron(III)-peroxo, and high-valent iron(IV)-oxo intermediates. In this article, we highlight the major crystallographic, spectroscopic, and mechanistic advances of the past 20 years that have significantly enhanced our understanding of the mechanisms of O2activation and the key roles played by iron-based oxidants.
authors.affiliation: Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA.
authors.forename: Subhasree
authors.initials: S
authors.lastname: Kal
authors.affiliation: Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA. larryque@umn.edu.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
mesh_terms: D002264:Carboxylic Acids / Q000378:metabolism*; D004789:Enzyme Activation; D004798:Enzymes / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D004798:Enzymes; D016877:Oxidants; D007501:Iron; D010100:Oxygen
keywords: 2-His-1-carboxylate facial triad; Halogenases; Nonheme iron enzymes; O2 activation; Pterin-dependent hydroxylases; Rieske oxygenases; α-Ketoglutarate-dependent enzymes