An extended-X-ray-absorption-fine-structure study of bovine erythrocyte superoxide dismutase in aqueous solution. Direct evidence for three-co-ordinate Cu(I) in reduced enzyme.

N. J. Blackburn, S. S. Hasnain, N. Binsted, G. P. Diakun, C. D. Garner, P. F. Knowles

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92 Scopus citations

Abstract

Copper and zinc K-edge e.x.a.f.s. (extended X-ray-absorption fine structures) were measured for the metal sites of oxidized and reduced bovine superoxide dismutase in aqueous solution. Detailed analysis of the spectra indicates that the copper site of the enzyme changes on reduction and is most probably co-ordinated to three imidazole groups at a shorter distance Cu-N(alpha) = 0.194 nm (1.94 A) in the reduced form compared with a co-ordination of four imidazole groups at 0.199 nm (1.99 A) and an oxygen atom from solvent water at 0.224 nm (2.24 A) in the oxidized form. Examination of the edge, near-edge structure and e.x.a.f.s. of the zinc sites indicates that the stereochemical changes at copper that accompany reduction introduce minimal perturbation on the stereochemistry at zinc.

Original languageEnglish (US)
Pages (from-to)985-990
Number of pages6
JournalThe Biochemical journal
Volume219
Issue number3
DOIs
StatePublished - May 1 1984

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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