Schullery S E, Miller R H
Biochim Biophys Acta. 1977 Aug 1;468(3):451-60. doi: 10.1016/0005-2736(77)90294-2.
The binding of uranyl ion, UO2+2, to egg phosphatidylcholine liposomes was studied as a potential method for the determination of liposome surface areas. Unbound uranyl was determined spectrophotometrically as the Arsenazo III complex with centrifuge supernatant. There is an apparent positive cooperativity in uranyl binding at phosphatidylcholine concentrations above approx. 0.1 mM. The binding capacity per mol increases upon liposome dilution. The data are consistent with liposomes existing in a highly aggregated state. The binding constant in the limit of low concentration of bound uranyl was 9+/-3)-10(6) M-1 in 0.1 M NaCl, pH 4.1. At saturation about four uranyl ions are bound per 100 phosphatidylcholine molecules. Relative surface areas of different dispersions may be calculated from intercepts of extrapolated binding isotherms, and absolute surface areas may be calculated if a value for the uranyl-phosphatidylcholine stoichiometry is assumed.
研究了铀酰离子（UO2+2）与鸡蛋磷脂酰胆碱脂质体的结合情况，将其作为一种测定脂质体表面积的潜在方法。未结合的铀酰通过分光光度法测定，以离心上清液中与偶氮胂III形成的络合物形式存在。在磷脂酰胆碱浓度高于约0.1 mM时，铀酰结合存在明显的正协同效应。脂质体稀释时，每摩尔的结合能力增加。这些数据与脂质体以高度聚集状态存在相一致。在0.1 M NaCl、pH 4.1条件下，结合的铀酰浓度较低时的结合常数为(9±3)×10(6) M-1。在饱和状态下，每100个磷脂酰胆碱分子约结合4个铀酰离子。不同分散体系的相对表面积可根据外推结合等温线的截距计算得出，若假设铀酰 - 磷脂酰胆碱化学计量关系的值，则可计算出绝对表面积。
