title: High-potential states of blue and purple copper proteins.
abstract: Electrochemical measurements show that there are high-potential states of two copper proteins, Pseudomonas aeruginosa azurin and Thermus thermophilus CuA domain; these perturbed states are formed in guanidine hydrochloride (GuHCl) solution in which the proteins are still blue (azurin) and purple (CuA). In each case, the high-potential state forms reversibly. Absorption (azurin, CuA), visible circular dichroism (azurin, CuA), resonance-Raman (CuA), and EPR (CuA) spectra indicate that the structure of the oxidized copper site of each high-potential form is very similar to that of the native protein. It is proposed that GuHCl perturbs one or more H-bonds in the blue or purple copper active site, thereby allowing Cu(I) to adopt a more favorable coordination structure than that in the rigid cavity of the native protein.
authors.affiliation: Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA. pernilla@cco.caltech.edu
authors.forename: P
authors.initials: P
authors.lastname: Wittung-Stafshede
authors.forename: E
authors.initials: E
authors.lastname: Gomez
authors.forename: A
authors.initials: A
authors.lastname: Ohman
authors.forename: R
authors.initials: R
authors.lastname: Aasa
authors.forename: R M
authors.initials: RM
authors.lastname: Villahermosa
authors.forename: J
authors.initials: J
authors.lastname: Leckner
authors.forename: B G
authors.initials: BG
authors.lastname: Karlsson
authors.forename: D
authors.initials: D
authors.lastname: Sanders
authors.forename: J A
authors.initials: JA
authors.lastname: Fee
authors.forename: J R
authors.initials: JR
authors.lastname: Winkler
authors.forename: B G
authors.initials: BG
authors.lastname: Malmström
authors.forename: H B
authors.initials: HB
authors.lastname: Gray
authors.forename: M G
authors.initials: MG
authors.lastname: Hill
mesh_terms: D001400:Azurin / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry*; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000737:chemistry*; D019791:Guanidine / Q000494:pharmacology; D006860:Hydrogen Bonding; D008667:Metalloproteins / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011489:Protein Denaturation; D017510:Protein Folding; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D016963:Thermus thermophilus / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; D001400:Azurin; D003300:Copper; D003576:Electron Transport Complex IV; D019791:Guanidine