Description
Residual oxygen consumption, ROX, is the respiration due to oxidative side reactions remaining after application of ETS inhibitors to mitochondrial preparations or cells, or in mt-preparations incubated without substrates (in the presence of ADP: State 2). Mitochondrial resipration is frequently corrected for ROX, then distinguishing ROX-corrected ROUTINE, LEAK, OXPHOS or ETS (R, L, P and E) from the corresponding apparent fluxes that have not been corrected for ROX (RΒ΄, LΒ΄, PΒ΄ and EΒ΄). When expressing ROX as a fraction of total respiration (flux control ratio), apparent flux not corrected for ROX should be taken as the reference. ROX may be related to, but is of course different from ROS production.
Abbreviation: ROX
Reference: Gnaiger 2014 MitoPathways, Gnaiger 2009 Int J Biochem Cell Biol
Keilin 1929: Residual respiration
'KCN, H2S and CO combine with some of the components of oxidase forming an inactive compound, with the result that cytochrome, or at least its components aβ and cβ, as well as paraphenylenediamine added to the cells, are not oxidised. The respiratory process can be still carried out through the medium of some autoxidisable carriers such as haemochromogens, haematins, the component bβ of cytochrome, or some as yet unknown autoxidisable substances. This residual respiration, according to the nature of the cell, may represent a larger or smaller fraction of the total respiration of the cell.'
- Keilin D (1929) Cytochrome and respiratory enzymes. Proc R Soc London Ser B 104:206-52.
ROX and non-mitochondrial respiration
Residual oxygen consumption (ROX) is sometimes referred to as 'non-mitochondrial respiration'. This may be correct to a large extent, but is not entirely accurate. In a preparation of purified isolated mitochondria, a small but significant ROX is observed, even after correction for instrumental background oxygen flux. In this case, ROX is 'mitochondrial non-ETS' rather than βnon-mitochondrialβ respiration. In permeabilized and intact cells, ROX may be higher than in isolated mitochondria, and this increased part then would be the best measurement of non-mitochondrial respiration.
Related terms in Bioblast
OXPHOS, P
ROUTINE, R
ETS, E
LEAK, L
ROX, R