title: The type 1 copper site of pseudoazurin: axial and rhombic.
abstract: We report on a high-frequency electron-paramagnetic-resonance study of the type 1 copper site of pseudoazurin. The spectra fully resolve the contribution of a nearly axial spectrum besides the rhombic spectrum, which unequivocally proves the existence of two conformations of the copper site. Pseudoazurins have been considered from Achromobacter cycloclastes including eight mutants and from Alcaligenes faecalis. The two conformations are virtually the same for all pseudoazurins, but the rhombic/axial population varies largely, between 91/9 and 33/67. These observations are discussed in relation to optical absorption spectra and X-ray diffraction structures. A similar observation for fern plastocyanin from Dryopteris crassirhizoma suggests that dual conformations of type 1 copper sites are more common.
authors.affiliation: Leiden University, Department of Physics, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, The Netherlands. Electronic address: gast@physics.leidenuniv.nl.
authors.forename: Peter
authors.initials: P
authors.lastname: Gast
authors.affiliation: Leiden University, Department of Physics, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, The Netherlands.
authors.forename: Freek G J
authors.initials: FG
authors.lastname: Broeren
authors.affiliation: Leiden University, Department of Physics, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, The Netherlands.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sottini
authors.affiliation: Ibaraki University, Institute of Applied Beam Sciences, Mito, Ibaraki 3108512, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Aoki
authors.affiliation: Ibaraki University, Institute of Applied Beam Sciences, Mito, Ibaraki 3108512, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Takashina
authors.affiliation: Ibaraki University, Institute of Applied Beam Sciences, Mito, Ibaraki 3108512, Japan.
authors.forename: Takahide
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Ibaraki University, Institute of Applied Beam Sciences, Mito, Ibaraki 3108512, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Kohzuma
authors.affiliation: Leiden University, Department of Physics, Huygens-Kamerlingh Onnes Laboratory, P.O. Box 9504, NL-2300 RA Leiden, The Netherlands.
authors.forename: Edgar J J
authors.initials: EJ
authors.lastname: Groenen
mesh_terms: D042422:Achromobacter cycloclastes / Q000737:chemistry; D042481:Alcaligenes faecalis / Q000737:chemistry; D001400:Azurin / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D010970:Plastocyanin / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: C047163:pseudoazurin; D001400:Azurin; D003300:Copper; D010970:Plastocyanin
keywords: 275GHz EPR; Absorption spectrum; Blue copper sites; Plastocyanin; Pseudoazurin; Type 1 copper