title: Cytoglobin conformations and disulfide bond formation.
abstract: The oligomeric state and kinetics of ligand binding were measured for wild-type cytoglobin. Cytoglobin has the classical globin fold, with an extension at each extremity of about 20 residues. The extended length of cytoglobin leads to an ambiguous interpretation of its oligomeric state. Although the hydrodynamic diameter corresponds to that of a dimer, it displays a mass of a single subunit, indicating a monomeric form. Thus, rather than displaying a compact globular form, cytoglobin behaves hydrodynamically like a tightly packed globin with a greater flexibility of the N- and C-terminal regions. Cytoglobin displays biphasic kinetics after the photolysis of CO, as a result of competition with an internal protein ligand, the E7 distal histidine. An internal disulfide bond may form which modifies the rate of dissociation of the distal histidine and apparently leads to different cytoglobin conformations, which may affect the observed oxygen affinity by an order of magnitude.
authors.affiliation: Inserm U779, Universités Paris VI et XI, Le Kremlin-Bicêtre, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lechauve
authors.forename: Cédric
authors.initials: C
authors.lastname: Chauvierre
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Brian N
authors.initials: BN
authors.lastname: Green
authors.forename: Michael C
authors.initials: MC
authors.lastname: Marden
authors.forename: Chantal
authors.initials: C
authors.lastname: Célier
authors.forename: Laurent
authors.initials: L
authors.lastname: Kiger
mesh_terms: D000078842:Cytoglobin; D004220:Disulfides / Q000737:chemistry*; D005914:Globins / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D007700:Kinetics; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000078842:Cytoglobin; D004220:Disulfides; D006639:Histidine; D005914:Globins