BIOMAT Database Logo BIOMAT Database Logo

Nature and functional implications of the cytochrome a3 transients after photodissociation of CO-cytochrome oxidase. 1991

W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
INC-4, Los Alamos National Laboratory, NM 87545.

Time-resolved electronic absorption, infrared, resonance Raman, and magnetic circular dichroism spectroscopies are applied to characterization of the intermediate that is formed within 20 ps after photodissociation of CO from cytochrome a3 in reduced cytochrome oxidase. This intermediate decays with the same half-life (approximately 1 microseconds) as the post-photodissociation CU+B-CO species previously observed by time-resolved infrared. The transient UV/visible spectra, kinetics, infrared, and Raman evidence suggest that an endogenous ligand is transferred from CuB to Fea3 when CO binds to CuB, forming a cytochrome a3 species with axial ligation that differs from the reduced unliganded enzyme. The time-resolved magnetic circular dichroism results suggest that this transient is high-spin and, therefore, five-coordinate. Thus we infer that the ligand from CuB binds on the distal side of cytochrome a3 and displaces the proximal histidine imidazole. This remarkable mechanistic feature is an additional aspect of the previously proposed "ligand-shuttle" activity of the CuB/Fea3 pair. We speculate as to the identity of the ligand that is transferred between CuB and Fea3 and suggest that the ligand shuttle may play a functional role in redox-linked proton translocation by the enzyme.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D010782 Photolysis Chemical bond cleavage reactions resulting from absorption of radiant energy. Photodegradation
D011487 Protein Conformation The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain). Conformation, Protein,Conformations, Protein,Protein Conformations
D002248 Carbon Monoxide Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed) Monoxide, Carbon
D003576 Electron Transport Complex IV A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane. Cytochrome Oxidase,Cytochrome aa3,Cytochrome-c Oxidase,Cytochrome Oxidase Subunit III,Cytochrome a,a3,Cytochrome c Oxidase Subunit VIa,Cytochrome-c Oxidase (Complex IV),Cytochrome-c Oxidase Subunit III,Cytochrome-c Oxidase Subunit IV,Ferrocytochrome c Oxygen Oxidoreductase,Heme aa3 Cytochrome Oxidase,Pre-CTOX p25,Signal Peptide p25-Subunit IV Cytochrome Oxidase,Subunit III, Cytochrome Oxidase,p25 Presequence Peptide-Cytochrome Oxidase,Cytochrome c Oxidase,Cytochrome c Oxidase Subunit III,Cytochrome c Oxidase Subunit IV,Oxidase, Cytochrome,Oxidase, Cytochrome-c,Signal Peptide p25 Subunit IV Cytochrome Oxidase,p25 Presequence Peptide Cytochrome Oxidase
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013059 Spectrum Analysis, Raman Analysis of the intensity of Raman scattering of monochromatic light as a function of frequency of the scattered light. Raman Spectroscopy,Analysis, Raman Spectrum,Raman Optical Activity Spectroscopy,Raman Scattering,Raman Spectrum Analysis,Scattering, Raman,Spectroscopy, Raman
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

Related Publications

W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
Electron-transfer processes in carboxy-cytochrome c oxidase after photodissociation of cytochrome a3 2+ . CO.
August 1979, Biochimica et biophysica acta,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
Heme-heme interactions in cytochrome c oxidase: effects of photodissociation of the CO compound.
September 1972, Biochemical and biophysical research communications,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
Biochemical and biophysical studies on cytochrome c oxidase. XVII. An epr study of the photodissociation of cytochrome a32+-CO.
May 1974, Biochimica et biophysica acta,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
The interactions of copper and a3 in cytochrome oxidase.
March 1970, Biochemical and biophysical research communications,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
New transients in the electron-transfer dynamics of photolyzed mixed-valence CO-cytochrome c oxidase.
August 1992, Proceedings of the National Academy of Sciences of the United States of America,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
Cytochrome a3 structure in carbon monoxide-bound cytochrome oxidase.
July 1984, Science (New York, N.Y.),
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
On cytochrome c oxidase. I. The extinction coefficients of cytochrome a and cytochrome a3.
April 1966, Biochimica et biophysica acta,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
Photodissociation of cytochrome c oxidase-nitric oxide complexes.
January 1988, Annals of the New York Academy of Sciences,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
On cytochrome c oxidase. II. The ratio of cytochrome a to cytochrome a3.
April 1966, Biochimica et biophysica acta,
W H Woodruff, and O Einarsdóttir, and R B Dyer, and K A Bagley, and G Palmer, and S J Atherton, and R A Goldbeck, and T D Dawes, and D S Kliger
A Functional Model of Cytochrome c Oxidase: Thermodynamic Implications.
December 1998, Angewandte Chemie (International ed. in English),
Copied contents to your clipboard!