Bonincontro A, Spigone E, Ruiz Peña M, Letizia C, La Mesa C
CNISM-Department of Physics, University of Rome La Sapienza, P. le A. Moro 5, I-00185 Roma, Italy.
J Colloid Interface Sci. 2006 Dec 15;304(2):342-7. doi: 10.1016/j.jcis.2006.09.046. Epub 2006 Sep 23.
Mixing aqueous sodium dodecylsulfate with cetyltrimethylammonium bromide solutions in mole ratios close to (1.7/1.0) allows the formation of cat-anionic vesicles with an excess of negative charges on the outer surface. The vesicular dispersions are mixed with lysozyme, and interact electrostatically with the positive charges on the protein, forming lipo-plexes. Dielectric relaxation, zeta-potential, and light scattering indicate the occurrence of interactions between vesicles and the protein. According to CD, the vesicle-adsorbed protein retains its native conformation. Binding and surface saturation, inferred by dielectric relaxation and zeta-potential, fulfil a charge neutralisation stoichiometry. Adsorbed lysozyme promotes the vesicle clustering and is concomitant with the lipo-plexes flocculation. Above the charge neutralisation threshold, lysozyme in excess remains dispersed in molecular form. Attempts were made to determine in what conditions protein release from the vesicles occurs. Accordingly, the full neutralisation of sodium dodecylsulfate in excess by cetyltrimethylammonium bromide ensures the lipo-plexes break-up, the precipitation of the mixed surfactants and the protein release in native form.
将十二烷基硫酸钠水溶液与十六烷基三甲基溴化铵溶液按接近（1.7/1.0）的摩尔比混合，可形成外表面带有过量负电荷的阴阳离子囊泡。将囊泡分散液与溶菌酶混合，其与蛋白质上的正电荷发生静电相互作用，形成脂质复合物。介电弛豫、ζ电位和光散射表明囊泡与蛋白质之间发生了相互作用。根据圆二色光谱，吸附在囊泡上的蛋白质保持其天然构象。通过介电弛豫和ζ电位推断的结合和表面饱和符合电荷中和化学计量。吸附的溶菌酶促进囊泡聚集，并伴随着脂质复合物的絮凝。在电荷中和阈值以上，过量的溶菌酶以分子形式保持分散状态。人们试图确定囊泡在何种条件下发生蛋白质释放。因此，十六烷基三甲基溴化铵将过量的十二烷基硫酸钠完全中和，确保脂质复合物分解、混合表面活性剂沉淀以及蛋白质以天然形式释放。
