Electrical current generation and proton pumping catalyzed by the ba 3‐type cytochrome c oxidase from Thermus thermophilus

FEBS Letters

Bamberg, Ernst¹  Buse, Gerhard³  Michel, Hartmut²  Kannt, Aimo²  Becker, Anja¹  Soulimane, Tewfik³ 

[1] Max-Planck-Institut für Biophysik, Abteilung Biophysikalische Chemie, Kennedyallee 70, D-60596 Frankfurt/M., Germany;Max-Planck-Institut für Biophysik, Abteilung Molekulare Membranbiologie, Heinrich-Hoffmann-Strasse 7, D-60528 Frankfurt/M., Germany;Institut für Biochemie, Klinikum der RWTH Aachen, Pauwelstrasse 30, D-52057 Aachen, Germany

关键词: Cytochrome c oxidase;    Cytochrome ba 3;    Proton pumping;    Black lipid membrane;    Thermus thermophilus;    BLM;    black lipid membrane;    CCCP;    carbonyl cyanide m-chlorophenylhydrazine;    P. denitrificans;    Paracoccus denitrificans;    Rubpy;    RuII(2;    2′-bipyridyl)3Cl2;    TAME;    N-α-tosyl-l-arginyl-O-methyl ester;    Th. thermophilus;    Thermus thermophilus;    1799;    1;    1;    1;    7;    7;    7-hexafluoro-2;    6-bis(trifluoromethyl)heptane-1;   

DOI  :  10.1016/S0014-5793(98)00942-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Several amino acid residues that have been shown to be essential for proton transfer in most cytochrome c oxidases are not conserved in the ba ₃-type cytochrome c oxidase from the thermophilic eubacterium Thermus thermophilus. So far, it has been unclear whether the Th. thermophilus ba ₃-type cytochrome c oxidase can nevertheless function as an electrogenic proton pump. In this study, we have combined charge translocation measurements on a lipid bilayer with two independent methods of proton pumping measurements to show that enzymatic turnover of the Th. thermophilus cytochrome c oxidase is indeed coupled to the generation of an electrocurrent and proton pumping across the membrane. In addition to a ‘vectorial’ consumption of 1.0 H⁺/e⁻ for water formation, proton pumping with a stoichiometry of 0.4–0.5 H⁺/e⁻ was observed. The implications of these findings for the mechanism of redox-coupled proton transfer in this unusual cytochrome c oxidase are discussed.

【 授权许可】

Unknown