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Bioblasts - Richard Altmann and MiPArt by Odra Noel
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Pyruvic acid

Pyruvic acid, C3H4O3, is an alpha-keto monocarboxylic acid which occurs under physiological conditions mainly as the anion pyruvate-, P, with pKa = 2.5. Pyruvate is formed in glycolysis from phosphoenolpyruvate. In the cytosol, pyruvate is a substrate of lactate dehydrogenase. Pyruvate enters the mitochondrial matrix via a specific low Km' H+/monocarboxylate cotransporter known as the pyruvate carrier. Similarly, the plasma membrane of many cell types has H+/monocarboxylate cotransporter activity and pyruvate can thus be added as a substrate to living cells. In the mt-matrix the oxidative decarboxylation of pyruvate is catalyzed by pyruvate dehydrogenase and yields acetyl-CoA. Pyruvate competitively reverses the inhibition of cytochrome c oxidase by cyanide. Pyruvate is an antioxidant reacting with hydrogen peroxide.

Abbreviation: P

Reference: Gnaiger 2014 MitoPathways, MiPNet09.12 O2k-Titrations

Application in HRR

P: Pyruvate (pyruvic acid, sodium salt, C3H3O3Na); Sigma P 2256, 25 g, store at 4 °C; FW = 110.0
Preparation of 2 M stock solution (dissolved in H2O)
  1. Prepare fresh everyday.
  2. Weigh 44 mg of pyruvic acid directly into a 0.5 mL Eppendorf tube.
  3. Add 0.2 mL H2O.
  4. Adjust pH to 7.0.
It is possible to weigh the powder beforehand in the Eppendorf-type tubes and store these tubes at 4 °C, to be diluted only on the day of use.

» O2k manual titrations MiPNet09.12 O2k-Titrations
  • Titration volume: 5 µL using a 25 µL syringe (2 mL O2k-chamber).
  • Final concentration: 5 mM.


Unstable respiration while using pyruvate as the only substrate

I am evaluating mitochondrial respiration from Drosophila melanogaster using Pyruvate, ADP, and Cytochrome C. However, I do not achieve a steady state level in OXPHOS.
Any advice would be appreciated. The data is attached (2019-07-17).
  • Answer:
    Pyruvate alone is not sufficient to support NADH-linked respiration. In order to do so you need to combine pyruvate with at least a second NADH-linked substrate (e.g., Malate) or use a more complex combination of substrates (e.g., Pyruvate&Glutamate&Malate). See Fig. 5.9. in Gnaiger 2014 MitoPathways
Additionally, you may consult some of the publications from Drosophila melanogaster mitochondria: O2k-Publications:_Drosophila

MitoPedia topics: Substrate and metabolite