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-l or 'blue'-copper protein from Thio6acillusferrooxidans. 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.