High-potential states of blue and purple copper proteins.
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.
Wittung-Stafshede
P
P
Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA. pernilla@cco.caltech.edu
Gomez
E
E
Ohman
A
A
Aasa
R
R
Villahermosa
R M
RM
Leckner
J
J
Karlsson
B G
BG
Sanders
D
D
Fee
J A
JA
Winkler
J R
JR
Malmström
B G
BG
Gray
H B
HB
Hill
M G
MG
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*
D001426:Bacterial Proteins; D008667:Metalloproteins; D001400:Azurin; D003300:Copper; D003576:Electron Transport Complex IV; D019791:Guanidine