The study of uncoupling action mechanism
of SkQ-SkQ3 family compounds

S.A. Eremeyev, K.A. Motovilov, L.S. Yaguzhinsky
A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University

Earlier in our work it was demonstrated that under conditions of mitochondrial proton pumps activation on the outer side of inner mitochondrial membrane the special fraction of protons is formed. These protons are nonequilibrium bounded with membrane and take part in ATP synthesis directly. Hydrogen ions of this fraction do not interact effectively with classic uncouplers. It was found out that weak Lewis bases (such as HEPES, MES, citrate) decrease the volume of the proton fraction discussed dew to catalysis of dissociation reaction of these protons from membrane surface into aqueous volume. We synthesized and tested new type of uncouplers (2,4,6-trichloro-3-pentadecylphenol,TCP-C15) with significantly increased affinity to membrane. It was shown that TCP-C15 selectively interacts with nonequilibrium membrane bounded protons. Removal of these protons by catalyst (HEPES) leads to dissipation of TCP-C15 uncoupling effect. However the uncoupling effect of classical uncoupler pentachlorophenol (PCP) remains unchanged in same conditions. In actual investigation we have demonstrated that addition of SkQ3 to mitochondria induces increase of respiration like the addition of TCP-C15 it does. This effect can be significantly decreased by higher concentration of catalyst (HEPES). The results obtained led us to preliminary conclusion that high membrane-acting properties of SkQ3 provide this substance with ability to interact with nonequilibrium membrane bounded protons effectively. In the general case SkQ3 may induce uncoupling effect by two ways: as single proton carrier and (in accordance to Severin F.F. et al.) as penetrating complex with fatty acid anions.

Severin F.F., Severina I.I., Antonenko Y.N., Rokitskaya T.I., Cherepanov D.A., Mokhova E.N., Vyssokikh M.Y., Pustovidko A.V., Markova O.V., Yaguzhinsky L.S., Korshunova G.A., Sumbatyan N.V., Skulachev M.V., Skulachev V.P. Penetrating cation/fatty acid anion pair as a mitochondria-targeted protonophore. Proc. Natl. Acad. Sci. USA. (2010);107(2):663-8.

Homo Sapiens Liberatus Workshop, Moscow State University, May 2010