Kinetics of membrane micellization by the hydrophobic polyelectrolyte poly(2-ethylacrylic acid)

被引:23
作者
Thomas, JL
Devlin, BP
Tirrell, DA
机构
[1] Dept. of Poly. Sci. and Engineering, University of Massachusetts, Amherst
来源
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES | 1996年 / 1278卷 / 01期
基金
美国国家科学基金会;
关键词
phosphatidylcholine; phosphatidylglycerol; polyelectrolyte; micellization; adsorption; kinetics;
D O I
10.1016/0005-2736(95)00192-1
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Rates of pH-dependent micellization of multilamellar vesicles by the hydrophobic polyelectrolyte poly(2-ethylacrylic acid) (PEAA) have been measured turbidometrically. This polymer shows a strong pH-dependence in its affinity for phospholipid membranes, binding in increasing amounts as pH is lowered and ultimately solubilizing membranes to form mixed micelles (Tirrell, Takigawa and Seki (1985) Ann. N.Y. Acad, Sci. 446, 237). The rate of solubilization of dipalmitoylphosphatidylcholine (DPPC) vesicle suspensions by PEAA increases approximately linearly with reductions in pH below a threshold at pH 6.55. Interestingly, negatively-charged dipalmitoylphosphatidylglycerol membranes showed qualitatively similar behavior in the presence of PEAA, and incorporation of 10% or 20% dipalmitoylphosphatidic acid in DPPC membranes did not affect solubilization rates, demonstrating that membrane charge is not an important factor in determining micellization kinetics. Micellization of DPPC and dimyristoylphosphatidylcholine membranes occurs most rapidly at their respective gel-liquid crystalline transition temperatures (T-m); the rate enhancement is correlated with a peak in the temperature-dependent binding of a fluorescently-modified PEAA in slightly alkaline solutions in which no micellization is observed. The lateral compressibility of the membrane, which has a similar peak at T-m, is proposed to be an important determinant of the rate and extent of polymer adsorption, and consequently of the rate of micellization.
引用
收藏
页码:73 / 78
页数:6
相关论文
共 30 条