title: Tuning the geometries of a de novo blue copper protein by axial interactions.
abstract: The axial interactions of Cu(2+) in type 1 copper proteins control the physical characteristics of the proteins. We tuned the geometries of a de novo designed blue copper protein with a four-helical bundle structure. The designed protein axially bound various ligands, such as chloride, phosphate, sulfate, acetate, azide, and imidazole, to Cu(2+), exhibiting a blue or green color. The UV-vis spectral bands were observed at approximately 600 nm and approximately 450 nm, with the A (~450)/A (~600) ratios between 0.14 and 1.58. The stronger axial interaction shifted the geometry of the type 1 copper site from trigonal planar geometry (blue copper) toward a tetrahedral-like geometry (green copper). Resonance Raman spectral analyses showed that the phosphate-bound type had the highest-strength Cu-S bond, similar to that of plastocyanin. The chloride-bound type exhibited features similar to those of stellacyanin and nitrite reductase, and the imidazole-bound type exhibited features similar to those of azurin M121E mutant.
authors: Department of Material Sciences, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-chou, Nagoya, 466-8555, Japan.
authors: Daigo
authors: D
authors: Shiga
authors: Yusuke
authors: Y
authors: Hamano
authors: Misato
authors: M
authors: Kamei
authors: Yasuhiro
authors: Y
authors: Funahashi
authors: Hideki
authors: H
authors: Masuda
authors: Miyuki
authors: M
authors: Sakaguchi
authors: Takashi
authors: T
authors: Ogura
authors: Toshiki
authors: T
authors: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D001386:Azides / Q000737:chemistry; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D003116:Color; D008024:Ligands; D008969:Molecular Sequence Data
chemical_list: D001386:Azides; D002352:Carrier Proteins; D008024:Ligands; C023548:copper-binding protein