Extended X-ray absorption fine structure of copper in Cu/sub A/-depleted, p-(hydroxymercuri)benzoate-modified, and native cytochrome c oxidase

Journal Article · Tue Apr 21 04:00:00 EDT 1987 · Biochemistry; (United States)

OSTI ID:5511446

Li, P M; Gelles, J; Chan, S I

Cytochrome c oxidase contains four redox-active metal centers: two heme irons, cytochromes a and a/sub 3/, and two copper ions, Cu/sub A/ and Cu/sub B/. Due to the paucity of spectroscopic signatures for both copper sites in cytochrome c oxidase, the ligands and structures for these sites have remained ambiguous. The specific depletion of Cu/sub A/ from the p-(hydroxymercuri)benzoate- (pHMB-) modified cytochrome c oxidase recently reported is herein described. Characterization of this enzyme shows that the structures of the remaining metal centers are essentially unperturbed by the Cu/sub A/ modification and depletion. Copper extended X-ray absorption fine structure (EXAFS) measurements on the Cu/sub A/-depleted cytochrome c oxidase reveal coordination of three (N, O) ligands and one (S, Cl) ligand at the Cu/sub B/ site. Comparison of EXAFS results obtained for the Cu/sub A/-depleted, pHMB-modified, and unmodified control enzymes has allowed the deconvolution of the EXAFS in terms of the inner coordination spheres for Cu/sub A/ as well as Cu/sub B/. On the basis of these data, it is found that the structure for the Cu/sub A/ site is consistent with two (N,O) ligands and two S ligands.

• Research Organization: California Institute of Technology, Pasadena
• OSTI ID: 5511446
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:8; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
550602* -- Medicine-- External Radiation in Diagnostics-- (1980-)
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ABSORPTION SPECTROSCOPY
CHARGED PARTICLES
COPPER
CYTOCHROME OXIDASE
ELECTRON SPECTRA
ELEMENTS
ENDOR
ENZYMES
HAEM DEHYDROGENASES
IONS
LIGANDS
MAGNETIC RESONANCE
METALS
MOLECULAR STRUCTURE
OXIDOREDUCTASES
RESONANCE
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENTS
X-RAY SPECTROSCOPY