Fluorescence and calorimetric studies of phase transitions in phosphatidylcholine multilayers: kinetics of the pretransition.

摘要: Discrepancies between calorimetric and fluorescence depolarization monitoring of the pretransition in multilamellar vesicles synthetic phosphatidylcholines are shown to result primarily from slow rate this transition. The membrane-associated dye 1,6-diphenyl-1,3,5-hexatriene was used determine temperature for a series heating cooling scan rates. These temperatures, when plotted vs. rate, extrapolated linearly transition at zero-scan Tm = 29.8 +/- 0.8 degrees C. slopes obtained these plots yielded characteristic times 8 30 min. In addition, analysis temperature-jump experiments, assuming first-order kinetics, gave range 4--8 data taken suggest most likely value time 5 2 min, with larger values possibly explainable by supercooling effects. Slight differences calorimetrically fluorimetrically determined main temperatures appear perturbation phosphatidylcholine bilayer fluorescent probe.