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Energy‐dependent Complex I‐associated ubisemiquinones in submitochondrial particles
Author(s) -
Vinogradov A.D.,
Sled V.D.,
Burbaev D.S.,
Grivennikova V.G.,
Moroz I.A.,
Ohnishi T.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00803-h
Subject(s) - submitochondrial particle , chemistry , rotenone , proton , coupling constant , cluster (spacecraft) , electron paramagnetic resonance , oxidizing agent , chemical physics , nuclear magnetic resonance , mitochondrion , physics , biochemistry , organic chemistry , particle physics , quantum mechanics , computer science , programming language
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.