Flux control ratios (FCR), are ratios of oxygen flux in different respiratory control states, normalized for maximum flux in a common reference state, to obtain theoretical lower and upper limits of 0.0 and 1.0 (0% and 100%).
For a given protocol or set of respiratory protocols, flux control ratios provide a fingerprint of coupling and substrate control independent of (i) mt-content in cells or tissues, (ii) purification in preparations of isolated mitochondria, and (iii) assay conditions for determination of tissue mass or mt-markers external to a respiratory protocol (CS, protein, stereology, etc.). FCR obtained from a single respirometric incubation with sequential titrations (sequential protocol; SUIT protocol) provide an internal normalization, expressing respiratory control independent of mitochondrial content and thus independent of a marker for mitochondrial amount. FCR obtained from separate (parallel) protocols depend on equal distribution of subsamples obtained from a homogenous mt-preparation or determination of a common mitochondrial marker.
MitoPedia methods: Respirometry
MitoPedia O2k and high-resolution respirometry: DatLab
Flux control factor: normalization of mitochondrial respiration
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- The entire plot of oxygen flux can be transformed to a FCR. Click on 'Flux/Slope' in the pull-down menu. - MiPNet19.18E O2 flux analysis - DatLab 6.