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Bioblasts - Richard Altmann and MiPArt by Odra Noel
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In respiratory assays for cytochrome c oxidase activity (Complex IV, CIV), ascorbate is added as regenerating system for maintaining TMPD in a reduced state. As has to be titrated into the respiration medium prior to the addition of TMPD, otherwise the reaction velocity of autoxidation is permanently elevated.

Abbreviation: As

Reference: MiPNet06.06

MitoPedia topics: Substrate and metabolite 

Application in HRR

As: Ascorbate sodium salt (Sodium L-ascorbate); Sigma A 7631, 100 g, store at RT; FW = 198.1.
Caution: Light sensitive (store solution in a dark glass vial).
Preparation of 800 mM stock solution (dissolved in H2O):
  1. Weigh 1.584 g of ascorbate sodium salt and dissolve in 10 mL H2O
  2. To prevent autoxidation, adjust pH to approx. 6 with ascorbic acid (a 137.6 solution of pH 2).
  3. Divide into 0.2 mL portions.
  4. Store frozen at -20 °C.

O2k manual titrations: MiPNet09.12
  • Titration volume: 5 µL using a 25 µL syringe.
  • Final conc. in 2 mL O2k-chamber: 2 mM.