Carboxyatractyloside, Cat, is a highly selective and potent inhibitor of the adenine nucleotide translocator (ANT). Cat stabilizes the nucleoside binding site of ANT on the cytoplasmic (positive) side of the inner membrane and blocks the exchange of matrix ATP and cytoplasmic ADP. It causes stabilization of the c conformation of ANT leading to permeability transition pore (PTP) opening, loss of mitochondrial membrane potential, and apoptosis.
MitoPedia topics: Inhibitor
Application in HRR
- Cat: Carboxyatractyloside (carboxyatractyloside potassium salt from Xanthium sibiricum, C31H44O18S2*Kx); Sigma C 4992, 2 mg, store at -20 °C; FW = 802.99 (free acid basis); Alternative source: Merck 216201-5MG (Calbiochem, Carboxyatractyloside potassium salt from Xanthium sibiricum, C31H43O18S2K3*3H2O), 5 mg, store at -20 °C, FW = 939.1).
- Caution: Chemicals stored in the fridge or freezer should be allowed to reach room temperature before opening. Very toxic!
- Preparation of 5 mM stock solution (dissolved in H20):
- Weigh 4.7 mg carboxyatractyloside.
- Dissolve in 1 ml H2O.
- Divide into 0.2 ml aliquots.
- Store at -20 °C.
- O2k manual titrations » MiPNet09.12 O2k-Titrations
- Titration volume: 2 µl using a 10 µl Hamilton syringe (2 ml O2k-chamber).
- Final concenteration: 5 µM.
- Comment: Cat is considered to be much more specific than Atractyloside (Atr), and the effective concentration required is much much lower (µM). With Atr, a very high concentration (mM) is required for full inhibition. Cat appears to be little permeable to intact cells and can thus only be applied in permeabilized cells and tissues or in isolated mitochondria (Ruas 2016 PLOS_ONE).