Fig. 6.

Effect of lypolysis on fluidity of TGRL. A: The effect of lipolysis on the EPR spectra of doxyl-labeled stearic acid in VLDL (top three sets) or chylomicrons (bottom set). In each experiment, an equal amount of TGRL sample (200 mg/dl TG) was pretreated with LpL for 30 min to generate lypolysis products prior to addition of the 16-DSA spin label. The arrows in the chylomicron spectrum highlight the increase in the population of highly mobile lipids when the sample is pretreated with LpL (red tracing) as opposed to without LpL pretreatment (black tracing) indicating an increase in lipid fluidity after LpL treatment. B: Effect of lipolysis spin-labeled cholestanol was added slowly while stirring the lipoprotein sample at 37°C and incubated for 2 h prior to scanning. C: Domain interaction of apoE on synthetic lipid particles containing two different concentrations of cholesterol (9 mg/dl or 24 mg/dl). Particles were prepared from synthetic TG rich emulsions as described in Materials and Methods and then incubated with spin-labeled apoE4 or the E3-like protein for 1 h at 37°C, followed by EPR spectroscopy.