P/E control ratio

high-resolution terminology - matching measurements at high-resolution

P/E control ratio

Description

[[Description:: The OXPHOS control ratio or P/E coupling control ratio (OXPHOS/ETS; phosphorylation system control ratio) is an expression of the limitation of OXPHOS capacity by the phosphorylation system. The P/E ratio increases with increasing capacity of the phosphorylation system up to a maximum of 1.0 when it matches or is in excess of ETS capacity. P/E also increases with uncoupling. P/E increases from the lower boundary set by L/E (zero capacity of the phosphorylation system), to the upper limit of 1.0, when there is no limitation of P by the phosphorylation system or the proton backpressure (capacity of the phosphorylation system fully matches the ETS capacity; or if the system is fully uncoupled). It is important to separate the kinetic effect of ADP limitation from limitation by enzymatic capacity at saturating ADP concentration. » MiPNet article]]

Abbreviation: Has abbr::''P/E''

Reference: [[Info::Gnaiger 2014 MitoPathways, Gnaiger 2009 Int J Biochem Cell Biol, Pesta 2012 Methods Mol Biol]]

MitoPedia methods: Respirometry 

MitoPedia topics: MitoPedia topic::Respiratory control ratio 

P/E from mouse to man

Has title::Gnaiger E (2014) ''P/E'' from mouse to man. Mitochondr Physiol Network 2014-05-20.

Was written by::OROBOROS (Was published in year::2014) Was published in journal::MiPNet

Abstract: [[has abstract::Variability of the P/E depends in part on coupling of OXPHOS, but mainly results from a diversity in the apparent ETS excess capacity over the capacity of the phosphorylation system in different species, tissues and cell lines.]]

• O2k-Network Lab: Was published by MiPNetLab::AT Innsbruck Gnaiger E

Labels:

Regulation: Topic::Coupling efficiency;uncoupling  Coupling state: Coupling states::OXPHOS, Coupling states::ETS 

HRR: Instrument and method::Theory 

When using animal (specifically mouse) versus human muscle tissue, it is important to be aware of the fact that human muscle shows a significant apparent excess capacity of the ETS versus the phosphorylation system with physiological substrate combinations (P/E<1.0), in contrast to mouse skeletal and cardiac tissue (P/E=0.97 to 1.0). Therefore, uncoupler titrations (to estimate ETS capacity, E) following ADP stimulation (to estimate OXPHOS capacity, P) are different: The optimum uncoupler concentration can be estimated by stepwise titration from the P state to the E state in human muscle mitochondria. In mouse muscle mitochondria, this is not possible if P/E=1.0, since under these respiratory control conditions there is no stimulation of respiration at any uncoupler concentration, but only inhibition at increasing uncoupler concentrations.

To show the actual action of the uncoupler in such mitochondria, a control experiment must be carried out when titrating uncoupler in the absence of ADP, to see the actual stimulation from the LEAK state (L) to the ETS state (E).

Can P/E be higher than 1.0?

OXPHOS capacity can be less than or equal to ETS capacity, but it cannot be higher. Any result giving P/E>1.0 is due to an experimental artefact. Such an artefact may be obtained due to application of an inhibitory uncoupler concentration, or inhibition of ETS by inhibitors of a component of the phosphorylation system.

• The P/E ratio is also discussed in: ETS capacity

Biochemical coupling efficiency: from 0 to <1

• More details: Biochemical coupling efficiency

List of publications: OXPHOS and ETS

{{#ask: Coupling states::OXPHOS Coupling states::ETS |?Was published in year=Year |?Has title=Reference |?Mammal and model |?Tissue and cell |?Stress |?Diseases |format=broadtable |limit=5000 |offset=0 |sort=Was published in year |order=descending }}