?Interaction of FCCP with liposomes. Dependence on Temperature and on the Phase State?.

ANDREA C. CUTRÓ; OSCAR A. ROVERI

puerto Madryn

Simposio; XLVI Reunión Anual- Sociedad Argentina de Investigación en Bioquímica y Biología Molecular. IUBMB Symposium: ?MicroRNA and Small RNAs in Health and Disease; 2010

SAIB

FCCP (carbonilo cyanide p-trifluoromethoxyphenyl hydrazone) is a protonophoric uncoupler. However at a higher concentrations it exerts additional effects on the mitocondrial energy metabolismo. We have previously shown that the binding of aniline-naphtalene sulphonate (ANS) to liposomes is also affected by FCCP. We decided to study the effect of FCCP on the binding of ANS to DOPC liposomes at different temperatures (in the lamellar liquid crystalline mesophase) and to DPPC liposomes at 25ºC (gel phase) and 50ºC (liquid crystalline phase). When DOPC was used, IC50 (FCCP) values increases with temperature. Hence, the binding of FCCP to the bilayer is an exotermic process. The apparent Kd(ANS) also increases with temperature in the absence of FCCP, whereas it becomes independent of the temperature in its presence. Conversely, the apparent Kd(ANS) for the binding of ANS to DPPC liposomes at 50ºC is significantly lower than that obtained at 25ºC either in the absence or in the presence of FCCP. Hence, the membrane phase influences the binding of ANS differently than temperature. However, IC50(FCCP) values obtained with DPPC do not significantly differ from those obtained with DOPC liposomes. We can conclude that the binding of FCCP to the bilayer is not dependent on the mesophase, and suggest that penetration of FCCP in the bilayer is not required for the inhibition of ANS binding.