Reaction mechanism of single subunit NADH-ubiquinone oxidoreductase (Ndi1) from Saccharomyces cerevisiae: evidence for a ternary complex mechanism.

ABSTRACT: The flavoprotein rotenone-insensitive internal NADH-ubiquinone (UQ) oxidoreductase (Ndi1) is a member of the respiratory chain in Saccharomyces cerevisiae. We reported previously that bound UQ in Ndi1 plays a key role in preventing the generation of reactive oxygen species. Here, to elucidate this mechanism, we investigated biochemical properties of Ndi1 and its mutants in which highly conserved amino acid residues (presumably involved in NADH and/or UQ binding sites) were replaced. We found that wild-type Ndi1 formed a stable charge transfer (CT) complex (around 740 nm) with NADH, but not with NADPH, under anaerobic conditions. The intensity of the CT absorption band was significantly increased by the presence of bound UQ or externally added n-decylbenzoquinone. Interestingly, however, wh

SUBMITTER: Yang Y 

PROVIDER: S-EPMC3059053 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature