title: EPR investigation of the role of B10 phenylalanine in neuroglobin - evidence that B10Phe mediates structural changes in the heme region upon disulfide-bridge formation.
abstract: The function of neuroglobin, a member of the vertebrate globin family, is still unknown. In human neuroglobin (NGB), the formation of a disulfide bridge between the CysCD7 and CysD5 is known to affect the heme environment and its ligand-binding kinetics. Here, we show by means of EPR that the PheB10 residue plays a key role in transmitting the structural information from the disulfide bridge to the heme-pocket region. While formation of a disulfide bridge in ferric wild-type NGB leads to a considerable change of its EPR parameters, only minor changes are observed in the case of ferric PheB10Leu NGB. Furthermore, wild-type NGB is found to be much more stable in the presence of H(2)O(2) than its PheB10Leu or its HisE7Leu mutants. While tyrosyl radicals are induced in HisE7Leu NGB by the addition of H(2)O(2), this is not the case for wild-type and PheB10Leu NGB. The results will be discussed in terms of the protein's putative functions.
authors.affiliation: Department of Physics, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
authors.forename: Maria
authors.initials: M
authors.lastname: Ezhevskaya
authors.forename: Florin
authors.initials: F
authors.lastname: Trandafir
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
mesh_terms: D001921:Brain / Q000502:physiology*; D003001:Cloning, Molecular; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli; D005914:Globins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000078787:Neuroglobin; D010084:Oxidation-Reduction / Q000187:drug effects; D010649:Phenylalanine / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014169:Transformation, Bacterial
chemical_list: D004220:Disulfides; D008024:Ligands; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D011994:Recombinant Proteins; D006418:Heme; D010649:Phenylalanine; D005914:Globins; D006861:Hydrogen Peroxide; D003545:Cysteine