A Conserved Glutamic Acid in Helix VI of Cytochrome bo3 Influences a Key Step in Oxygen Reduction
| Autor: | Thomas Brittain, Jeffrey P. Osborne, Robert B. Gennis, Richard H. Little, Nicholas J. Watmough, Elizabeth Furlong-Nickels, Andromachi Katsonouri, Colin Greenwood |
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| Rok vydání: | 1997 |
| Předmět: |
inorganic chemicals
Cytochrome Stereochemistry Mutant Glutamic Acid Photochemistry Biochemistry Protein Structure Secondary Electron transfer Escherichia coli Amino Acid Sequence Conserved Sequence Alanine chemistry.chemical_classification biology Chemistry Escherichia coli Proteins Active site Glutamic acid Cytochrome b Group Kinetics Enzyme Amino Acid Substitution Spectrophotometry biology.protein Cytochromes Oxidation-Reduction Oxygen binding |
| Zdroj: | Biochemistry. 36:13736-13742 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi971434i |
| Popis: | We have compared the reactions with dioxygen of wild-type cytochrome bo3 and a mutant in which a conserved glutamic acid at position-286 of subunit I has been changed to an alanine. Flow-flash experiments reveal that oxygen binding and the rate of heme-heme electron transfer are unaffected by the mutation. Reaction of the fully (3-electron) reduced mutant cytochrome bo3 with dioxygen yields a binuclear center which is substantially in the P (peroxy) state, not the well-characterized F (oxyferryl) state which is the product of the reaction of the fully reduced wild-type enzyme with dioxygen [Puustinen, A., et al. (1996) Proc. Natl. Acad. Sci. U.S.A. 93, 1545-1548]. These results confirm that proton uptake is important in controlling the later stages of dioxygen reduction in heme-copper oxidases and show that E286 is an important component of the channel that delivers these protons to the active site. |
| Databáze: | OpenAIRE |
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