Energy‐dependent Complex I‐associated ubisemiquinones in submitochondrial particles

FEBS Letters

Vinogradov, A.D.¹  Burbaev, D.S.³  Ohnishi, T.²  Grivennikova, V.G.¹  Sled, V.D.²  Moroz, I.A.³ 

[1] Department of Biochemistry, School of Biology, Moscow State University, 119899 Moscow, Russian Federation;Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;Institute of Chemical Physics, Russian Academy of Science, 117977 Moscow, Russian Federation

关键词: NADH-ubiquinone oxidoreductase;    Energy-coupling;    Ubisemiquinone;    Iron-sulfur cluster;    EPR-spectroscopy;    Bovine heart submitochondrial particle;    HEPES;    N-2-hydroxyethylpiperazine-N-enanesulfonic acid;    CCCP;    carbonyl cyanide m-chlorophenyl hydrazone;    SMP;    submitochondrial particles;   

DOI  :  10.1016/0014-5793(95)00803-H

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Two distinct species of Complex I-associated ubisemiquinones (SQ_Nf and SQ_Ns) were detected by cryogenic EPR analysis of tightly coupled submitochondrial particles oxidizing NADH or succinate under steady-state conditions. The g = 2.00 signals from both fast-relaxing at 40 K) and slow-relaxing ) are sensitive to uncouplers, rotenone and thermally induced deactivation of Complex I. At higher temperatures the SQ_Nf signal is broadened and only the SQ_Ns, signal is seen (). The spin-spin interaction between SQ_Nf and the iron-sulfur cluster N2 was detected as split peaks of the 2.05 signal with a coupling constant of 1.65 mT, revealing their mutual distance of 8–11 Å. The data obtained are consistent with a model in which N2 and two interacting bound ubisemiquinone species are spatially arranged within the hydrophobic domain of Complex I, participating in the vectorial proton translocation.

【 授权许可】

Unknown