Resumen de Lipid peroxidation rates of dppc liposomes containing different amounts of oxidable lipids show opposite dependence with the temperature
María Cubillos, Eduardo Lissi, Elsa Abuin
The effect of temperature on the oxidation rates of arachidonic acid and linoleic acid incorporated into dipalmitoylphosphatidylcholine liposomes have been investigated. The reaction was started by the photolysis of 2,2'-azobis (2-amidino propane) in order to minimize the dependence of the initiation rate with temperature. Both positive and negative activation energies were obtained for the rate of the oxidation, depending on the amount of oxidable lipid (20% or 50% mol:mol) and the temperature range considered. Changes in the rigidity of the liposomes elicited by temperature were assessed by measuring the generalized polarization of 6-dodecanoyl-2 (dimethylamino naphthalene), Laurdan. The high increase in rate observed at low temperatures employing lipid mixtures that render liposomes in the gel phase is attributed to a reduced rate constant of the termination step of the oxidation chain
