Specificity of interactions of the surface-active protonophore 2,4,6-trichloro-3-pentadecylphenol with artificial and mitochondrial membranes

Membranotropic properties of the surface-active reagent 2,4,6-trichloro-3-pentadecylphenol (TCP-C15) have been studied. In preliminary investigations it was found that TCP-C15 acts as an uncoupler of oxidative phosphorylation, selectively interacting with a fraction of non-equilibrium membrane-bound protons that forms during the work of proton pumps. In this work we obtained the following results: (1) additional validation of the conclusions drawn from the previous experiments was acquired on modified preparations of liver mitochondria, in which the fraction of non-equilibrium membrane-bound protons did not form; (2) it was shown that binding of TCP-C15 to the liposome surface increases its negative ζ-potential; this proves that TCP-C15 binds to the surface of membranes in the negatively charged state; (3) on the BLM model it was found that under constant electric field (90 mV) TCP-C15 not only induces the transmembrane transfer of charge, but also induces a specific hydrogen ion affinity to the surface of lipid bilayer; (4) strong evidence of the ionophore activity of TCP-C15 was obtained on the same model; this allowed us to get a full scheme of uncoupling mechanism of TCP-C15 on mitochondria and to explain the action of a catalyst (HEPES, 20 mM), which blocks this mechanism.