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Bioblasts - Richard Altmann and MiPArt by Odra Noel
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Cyanide (usually added as KCN) is a competitive inhibitor of cytochcrome c oxidase (CIV). Inhibition is reversed by pyruvate and high oxygen levels.

Abbreviation: KCN

Reference: MiPNet09.12

MitoPedia topics: Inhibitor 

Application in HRR

Last update 2021-01-22

Inhibitor titrations, CIV-assay, alternative oxidase and ROX

Caution: Due to a confusion, a change in the procedure for preparing the KCN was done in April 2019 that recommended to prepare 20 mM KCN stock and titrate 100 µL. This now (2021-01-22) has been corrected to our previous recommendation of 1 M KCN stock solutions

Preparation of KCN stock

Kcn(KCN): Fluka 60178, 100 g, store at R.T.; M = 65.12 g·mol-1.
Caution: KCN is photosensitive and hygroscopic; HCN is volatile and very toxic!
Preparation of 0.5 M KCN stock solution (dissolved in H2O):
  1. Weigh 32.6 mg of KCN.
  2. Dissolve in 1 ml H2O.
  3. The pH of the solution is basic. Since the titration amount is low and HCN may evaporate during pH adjustment with HCl, the pH is not adjusted.
  4. Divide into 0.2 mL portions
  5. Store at -20 °C.
» O2k manual titrations MiPNet09.12 O2k-Titrations
  • Titration volume (2-mL O2k-chamber): 4 µL using a 10 µL Hamilton syringe.
  • Titration volume (0.5-mL O2k-chamber): 1 µL using a 10 µL Hamilton syringe.
  • Final concentration: 1 mM.

MitoPedia topics: Inhibitor