[Thermo-induced structural changes in lipoproteins of human plasma, studied with spin probes].

The thermo-induced structural changes in lipoproteins (LP) of human plasma were investigated by the electron paramagnetic resonance method, using 5-doxylstearate as a spin probe. LP were shown to undergo thermotropic transformations at temperatures specific for each LP type. Differences were found in the nature of temperature dependences of the order parameter for the probe localized in LP and for isolated lipids. The denser the LP, the more pronounced the differences. 5-Doxylstearate was shown to be localized not only in the lipid phase of LP, but also in the area of the protein--lipid contact. This indicates that 5-doxylstearate is a useful tool for the study of protein--lipid interactions in pathological processes coupled with their modifications.