title: Effect of circular permutation on the structure and function of type 1 blue copper center in azurin.
abstract: Type 1 copper (T1Cu) proteins are electron transfer (ET) proteins involved in many important biological processes. While the effects of changing primary and secondary coordination spheres in the T1Cu ET function have been extensively studied, few report has explored the effect of the overall protein structural perturbation on active site configuration or reduction potential of the protein, even though the protein scaffold has been proposed to play a critical role in enforcing the entatic or "rack-induced" state for ET functions. We herein report circular permutation of azurin by linking the N- and C-termini and creating new termini in the loops between 1stand 2ndβ strands or between 3rdand 4thβ strands. Characterization by electronic absorption, electron paramagnetic spectroscopies, as well as crystallography and cyclic voltammetry revealed that, while the overall structure and the primary coordination sphere of the circular permutated azurins remain the same as those of native azurin, their reduction potentials increased by 18 and 124 mV over that of WTAz. Such increases in reduction potentials can be attributed to subtle differences in the hydrogen-bonding network in secondary coordination sphere around the T1Cu center.
authors.affiliation: Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
authors.forename: Yang
authors.identifier: 0000-0002-0784-9715
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.
authors.forename: Igor D
authors.initials: ID
authors.lastname: Petrik
authors.affiliation: Reed College, Portland, Oregon, 97202.
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Chacón
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.
authors.forename: Parisa
authors.initials: P
authors.lastname: Hosseinzadeh
authors.affiliation: Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.|Tianjin University of Science and Technology, Tianjin, 300457, China.
authors.forename: Honghui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Institute of Environmental Health, Oregon Health and Science University, Portland, Oregon, 97239.
authors.forename: Ninian J
authors.initials: NJ
authors.lastname: Blackburn
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.|Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
mesh_terms: D001400:Azurin / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain; D003300:Copper / Q000737:chemistry*; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D001400:Azurin; D003300:Copper
keywords: azurin; circular permutation; reduction potential; secondary coordination sphere