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

本文用电子自旋共振(ESR)波谱技术研究了不同pH值对酸性磷脂二棕榈酰磷脂酸(DPPA)脂质体相变性质的影响。结果表明:DPPA脂质体随pH值的增加其相变温度降低。通过对测试条件的选择和波谱参数的测量,TEMPO标记的DPPA脂质体在HEPES溶液中ESR谱不出现疏水峰的原因,是由于仪器分辨率不够以及自旋标记探针TEMPO在DPPA脂质体脂双层疏水相中的超精细偶合常数Ao和各向同性go因子与它们在HEPES溶液中的值相近。

ESR STUDIES ON THE EFFECTS OF pH ON THE PHASE TRANSITION BEHAVOR OF DIPALMITOYLPHOSPHATIDIC ACID LIPOSOMES

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.