title: Time-resolved infrared spectroscopic studies of ligand dynamics in the active site from cytochrome c oxidase.
abstract: The catalytic site of heme-copper oxidases encompasses two close-lying ligand binding sites: the heme, where oxygen is bound and reduced and the CuB atom, which acts as ligand entry and release port. Diatomic gaseous ligands with a dipole moment, such as the signaling molecules carbon monoxide (CO) and nitric oxide (NO), carry clear infrared spectroscopic signatures in the different states that allow characterization of the dynamics of ligand transfer within, into and out of the active site using time-resolved infrared spectroscopy. We review the nature and diversity of these processes that have in particular been characterized with CO as ligand and which take place on time scales ranging from femtoseconds to milliseconds. These studies have advanced our understanding of the functional ligand pathways and reactivity in enzymes and more globally represent intriguing model systems for mechanisms of ligand motion in a confined protein environment. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
authors.affiliation: Laboratory of Optics and Biosciences, CNRS, Ecole polytechnique, 91128 Palaiseau, France; INSERM U696, 91128 Palaiseau, France.
authors.forename: Marten H
authors.initials: MH
authors.lastname: Vos
authors.affiliation: Laboratory of Optics and Biosciences, CNRS, Ecole polytechnique, 91128 Palaiseau, France; INSERM U696, 91128 Palaiseau, France.
authors.forename: Ursula
authors.initials: U
authors.lastname: Liebl
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008958:Models, Molecular; D013055:Spectrophotometry, Infrared / Q000379:methods
chemical_list: D008024:Ligands; D006418:Heme; D003300:Copper; D002248:Carbon Monoxide; D003576:Electron Transport Complex IV
keywords: Binuclear center; Cytochrome c oxidases; Heme proteins; Ligand dynamics; Time-resolved spectroscopy