title: Time-resolved single-turnover of ba3 oxidase from Thermus thermophilus.
abstract: The kinetics of the oxidation of fully-reduced ba(3) cytochrome c oxidase from Thermus thermophilus by oxygen were followed by time-resolved optical spectroscopy and electrometry. Four catalytic intermediates were resolved during this reaction. The chemical nature and the spectral properties of three intermediates (compounds A, P and O) reproduce the general features of aa(3)-type oxidases. However the F intermediate in ba(3) oxidase has a spectrum identical to the P state. This indicates that the proton taken up during the P-->F transition does not reside in the binuclear site but is rather transferred to the covalently cross-linked tyrosine near that site. The total charge translocation associated with the F-->O transition in ba(3) oxidase is close to that observed during the F-->O transition in the aa(3) oxidases. However, the P(R)-->F transition is characterized by significantly lower charge translocation, which probably reflects the overall lower measured pumping efficiency during multiple turnovers.
authors.affiliation: Department of Molecular Energetics of Microorganisms, A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Siletsky
authors.forename: Ilya
authors.initials: I
authors.lastname: Belevich
authors.forename: Audrius
authors.initials: A
authors.lastname: Jasaitis
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Konstantinov
authors.forename: Mårten
authors.initials: M
authors.lastname: Wikström
authors.forename: Tewfik
authors.initials: T
authors.lastname: Soulimane
authors.forename: Michael I
authors.initials: MI
authors.lastname: Verkhovsky
mesh_terms: D002384:Catalysis; D003573:Cytochrome b Group / Q000737:chemistry / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D013053:Spectrophotometry; D016963:Thermus thermophilus / Q000201:enzymology*
chemical_list: D003573:Cytochrome b Group; C058557:cytochrome ba3; D003576:Electron Transport Complex IV; D010100:Oxygen