Lysozyme binding onto catanionic vesicles

Mixing aq. SDS with cetyltrimethylammonium bromide solns. in mole ratios close to (1.7/1.0) allows the formation of cat-anionic vesicles with an excess of neg. charges on the outer surface. The vesicular dispersions are mixed with lysozyme, and interact electrostatically with the pos. charges on the protein, forming lipoplexes. Dielec. 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 satn., inferred by dielec. relaxation and zeta-potential, fulfil a charge neutralization stoichiometry. Adsorbed lysozyme promotes the vesicle clustering and is concomitant with the lipo-plexes flocculation. Above the charge neutralization threshold, lysozyme in excess remains dispersed in mol. form. Attempts were made to det. in what conditions protein release from the vesicles occurs. Accordingly, the full neutralization of SDS in excess by cetyltrimethylammonium bromide ensures the lipo-plexes break-up, the pptn. of the mixed surfactants and the protein release in native form.