title: Intersite structural rearrangement of the blue copper site induced by substrate binding: spectroscopic studies of a copper-containing nitrite reductase from Alcaligenes xylosoxidans NCIMB 11015.
abstract: A copper-containing nitrite reductase from Alcaligenes xylosoxidans NCIMB 11015 has its own unique blue or type 1 copper protein resonance Raman spectrum in the usual Cu-S(Cys) stretching region, nu(Cu-S(Cys)), with a pair of strong peaks at 412 and 420 cm(-1) and a weak peak at 364 cm(-1). The predominantly nu(Cu-S(Cys)) Raman bands at 412, 420, and 364 cm(-1) of the type 1 copper site all shifted to higher frequencies upon binding of nitrite to the type 2 copper site, and the resonance Raman difference spectra progressively intensified with the increments of nitrite ion concentration. Positive support for substrate binding to the type 2 copper is provided by the nu(Cu-S(Cys)) bands in the resonance Raman spectrum of a type 2 copper-depleted enzyme, which is insensitive to the presence of NO2-. The shift to higher frequency of the Raman bands of the type 1 copper center with the addition of nitrite ions suggests a stronger Cu-S(Cys) interaction in the substrate-bound A. xylosoxidans nitrite reductase.
authors.affiliation: Institute of Applied Beam Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan. kohzuma@mx.ibraki.ac.jp
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Kohzuma
authors.forename: Makiko
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Naoko
authors.initials: N
authors.lastname: Horikoshi
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nagatomo
authors.forename: Teizo
authors.initials: T
authors.lastname: Kitagawa
authors.forename: Roman S
authors.initials: RS
authors.lastname: Czernuszewicz
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification; D003300:Copper / Q000032:analysis*; D009572:Nitrite Reductases / Q000737:chemistry* / Q000302:isolation & purification; D009573:Nitrites / Q000737:chemistry; D013059:Spectrum Analysis, Raman
chemical_list: D001426:Bacterial Proteins; D009573:Nitrites; D003300:Copper; D009572:Nitrite Reductases