title: Oxygenated complex of cytochrome bd from Escherichia coli: stability and photolability.
abstract: Cytochrome bd is one of the two terminal ubiquinol oxidases in the respiratory chain of Escherichia coli catalyzing reduction of O2 to H2O. The enzyme is expressed under low oxygen tension; due to high affinity for O2 it is isolated mainly as a stable oxygenated complex. Direct measurement of O2 binding to heme d in the one-electron reduced isolated enzyme gives K(d(O2)) of approximately 280 nM. It is possible to photolyse the heme d oxy-complex by illumination of the enzyme for several minutes under microaerobic conditions; the light-induced difference absorption spectrum is virtually identical to the inverted spectrum of O2 binding to heme d.
authors.affiliation: Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki, P.O. Box 65 (Viikinkaari 1), FIN-00014 Helsinki, Finland.
authors.forename: Ilya
authors.initials: I
authors.lastname: Belevich
authors.forename: Vitaliy B
authors.initials: VB
authors.lastname: Borisov
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Konstantinov
authors.forename: Michael I
authors.initials: MI
authors.lastname: Verkhovsky
mesh_terms: D003573:Cytochrome b Group; D003580:Cytochromes / Q000235:genetics / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008027:Light; D009097:Multienzyme Complexes; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
chemical_list: D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli; D010100:Oxygen