ESR STUDIES ON THE EFFECTS OF pH ON THE PHASE TRANSITION BEHAVOR OF DIPALMITOYLPHOSPHATIDIC ACID LIPOSOMES
电子自旋共振波谱技术研究不同pH值对二棕榈酰磷脂酸脂质体相变性质的影响

The effect of pH on the phase transition behavior of acidic phosphlipid -dipalmitoylphosphatidic acid (DPPA) - have been studied by electron spin resonance (ESR) technique. Results show that the phase transition temperature of DPPA liposomes decreases with the increase of pH. By measuring the hyp-erfine conping constant A and isotropic go factor of spin probe TEMPO in different media, ive found that the TEMPO spectra in DPPA liposomes (in HEPES solution) tailel to emerge hydrophobic peakes that reported before was due to the insufficient difference of the spectroscopic parameters in both HEPES solution and the hydrophobic region of DPPA liposomes (pH 9.0) as well as the insufficient resolving power of spectrometer.