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Citrate synthase

From Bioblast

high-resolution terminology - matching measurements at high-resolution

Citrate synthase


Condensation of oxaloacetate with acetyl-CoA yields citrate as an entry into the TCA cycle. CS is located in the mt-matrix. CS activity is frequently used as a functional marker of the amount of mitochondria (mitochondrial elementary marker, mtE) for normalization of respiratory flux.

Abbreviation: CS

Reference: MiPNet17.04 CitrateSynthase

Normalization of respiratory flux for CS as a mitochondrial marker

Communicated by Gnaiger Erich last update 2020-04-19
Respiration of living or permeabilized cells, tissue homogenate or permeabilized tissue, and isolated mitochondria can be normalized for CS activity. Then marker-specific oxygen flux, JO2/CS [pmol∙s­-1∙IU­-1], is a quantitative measure of respiration that reflects mitochondrial quality, independent of mitochondrial density.
Several publications in peer-reviewed journals report respiration normalized for CS activity in units which do not make sense, e.g. [pmol∙s-­1∙mL­-1∙IU­-1], such that those numerical results are pointless. Clarification is obtained by strict definitions of normalization of rates (BEC 2020.1) and dimensional analysis, summarized in MiPNet 17.04.


Bioblast linkReferenceYear
Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed.
Gnaiger E et al ― MitoEAGLE Task Group (2020) Mitochondrial physiology.
Laboratory protocol: Citrate synthase a mitochondrial marker enzyme.


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MitoPedia topics: Enzyme