EXAFS of the type-1 copper site of rusticyanin.
Extended X-ray absorption fine structure (EXAFS) spectra at the Cu K-edge have been recorded of the oxidized and reduced form at pH 3.5 of rusticyanin, the type-1 or 'blue'-copper protein from Thiobacillus ferrooxidans. The EXAFS of oxidized rusticyanin is well simulated with models assuming a ligand set of 2 N(His) and 1 S(Cys) at 1.99 and 2.16 A, respectively. Upon reduction, the average Cu-N ligand distance increases by approx. 0.08A. For both redox states studied, the fit by the simulation is significantly improved by including a contribution of an additional sulfur ligand at approx. 2.8 A. From comparison with structural data of other blue-copper proteins, it is concluded that the copper coordination environment is relatively rigid, which may be a clue to its high redox potential.
Holt
S D
SD
Division of Chemistry, School of Natural Sciences, Hatfield Polytechnic, Herts, UK.
Piggott
B
B
Ingledew
W J
WJ
Feiters
M C
MC
Diakun
G P
GP
D001400:Azurin / Q000648:ultrastructure*; D001426:Bacterial Proteins / Q000648:ultrastructure*; D001665:Binding Sites; D003300:Copper; D008667:Metalloproteins / Q000648:ultrastructure*; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis; D013855:Thiobacillus / Q000032:analysis*; D014965:X-Rays
D001426:Bacterial Proteins; D008667:Metalloproteins; C012543:rusticyanin; D001400:Azurin; D003300:Copper