[Influence of the structure of lecithins on their interaction with cholesterol]

Interaction between cholesterine and phosphatidilcholines (PC) of three types: 1,2-disaturated (SS), 1,2-diunsaturated (UU) and 1-saturated-2-unsaturated (SU) was studied in bilayer vesicular membranes (BVM) by means of NMR-1H spectroscopy. BVM were obtained by sonification of aqueous (D2O) dispersions of individual (PC) and their mixtures. It is found that molecular special specificity of the interaction between PC AND cholesterine is preserved not only during phase division but also in the case when all the phospholipid components of the bilayer are in a liquid crystal state. At low content of cholesterine it favourably interacts with UU-PC, further on with the increase of concentration cholesterine starts to interact with SU- and SS-types of PC. It has been shown that such behaviour of cholesterine can not be explained by means of static models, i.e. by the differences in stability of its stechiometric complexes with CP molecules of different types. An attempt has been undertaken to interpret the selective character of PS-cholesterine interaction proceeding from the suggestion about the anisotropic character of lateral diffusion in the membranes, consisting of various structural types of PC.