Isolation and Characterisation of Subcomplexes of the Mitochondrial NADH: Ubiquinone Oxidoreductase (Complex I)
1994; Wiley; Volume: 226; Issue: 1 Linguagem: Inglês
10.1111/j.1432-1033.1994.0t237.x
ISSN1432-1033
AutoresMoshe Finel, Anna Majander, Jaana Tyynelä, A. Mariette P. De Jong, Simon P. J. Albracht, Måtin Wikström,
Tópico(s)Mitochondrial Function and Pathology
ResumoEnzymically active subcomplexes were purified from bovine mitochondrial NADH: ubiquinone oxidoreductase (complex I) by sucrose‐gradient centrifugation in the presence of detergents. These subcomplexes, named Iλ, IS, and IλS, catalyse ferricyanide and ubiquinone‐1 (Q‐1) reduction by NADH at similar rates to complex I, but do not catalyse the reduction of decylubiquinone. In addition, the Q‐1 reductase activity of all the subcomplexes is insensitive to rotenone. Chemical and EPR analyses of the subcomplexes show that FMN and all the Fe‐S clusters of complex I are present, but that the line shape of cluster 2 is modified. The smallest subcomplex, IλS, contains only approximately 13 subunits, as compared to approximately 22 in the previously described sub‐complex Iα [Finel, M., Skehel, J. M., Albracht, S. J. P., Fearnley, I. M. & Walker, J. E. (1992) Biochemistry 31 , 11425–11434], but it retains the 75, 51‐, 49‐, 30‐, 24‐, 23‐ (TYKY) and 20‐kDa (PSST) subunits, which are suggested to form a functional core that comprises the EPR‐detectable Fe‐S clusters 1–4, and FMN. The structural and functional implications of such an arrangement are discussed.
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