Surface structure of the two porcine low-density lipoprotein subclasses — a spin labelling study

Abstract

Porcine low-density lipoprotein (LDL) subclasses were spin-labelled at both protein and lipid sites. The surface structures of the two subclasses were compared. E.s.r. spectra of stearic acid spin-labels [I( m/ n)] and of androstanol spin-label indicated more restricted motion of the labels in LDL 2 ( d = 1.063−1.090 g/ml) than in LDL 1 ( d = 1.020−1.063 g/ml). Thermotropic change in the surface structure was found in both subclasses by both protein and lipid spin-labels, but at lower temperature in LDl 1, than in LDL 2. These results indicate the relationship between the size and the dynamics of the lipid components in the surface layer of the LDL subclasses.