Structure and Function Relationships in Cytochrome Bo(3) Oxidase and Cytochrome Bd-I Oxidase From Escherichia Coli

Structure and function relationships in the two terminal oxidases in Escherichia coli have been investigated. Cytochrome bo3 oxidase, a member of the heme/copper superfamily, is found to have a semiquinone intermediate during turnover of quinol. Additionally, after the quinol is consumed and turnover stops, the enzyme is found in a mixture of oxidation states, one of which is the elusive Peroxy species. No free radical species is observed in conjunction with the Peroxy species. Support for a cytochrome bo3 proton pumping mechanism is presented in which a histidine ligand for CuB dissociates upon reduction. The other terminal oxidase, cytochrome bd-I oxidase, is not related to the heme/copper superfamily and was studied through sequence analyses and ligand reactivity. Sequence analysis suggested conserved residues that were then mutated. Reactivity with ligands indicated that the active site of cytochrome bd is highly unusual in that heme d binds ligands but virtually always remains high-spin, five-coordinate.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

1999

Author dc:creator

• Osborne, Jeffrey P.

Contributors dc:contributor

• Gennis, Robert B.

• Biophysics, General

Language dc:language

eng

Identifier

(MiAaPQ)AAI9944956

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84906