EFFECT OF BILAYER PHASE-TRANSITIONS ON VESICLE STRUCTURE AND ITS INFLUENCE ON THE KINETICS OF VIOLOGEN REDUCTION

Vesicles were prepared from pure phosphatidylcholines (PC), phosphatidic acids (PA), or dioctadecyldimethylamonium bromide (DODAB). The aggregate structure was examined above and below the gel-to-liquid crystalline transition temperature (T-m) by means of cryo-transmission electron microscopy. The redox reaction between a membrane bound viologen and dithionite was studied in the different lipid systems. It was found that the presence of faceted vesicles or open bilayer fragments, below T-m, lead to double-exponential reduction kinetics.