Human Plasma Very Low-Density Lipoproteins Are Stabilized by Electrostatic Interactions and Destabilized by Acidic pH
Figure 4
Effects of pH on VLDL stability. Thermal denaturation of VLDL in 10 mM Na phosphate buffer at pH 8.2–6.0 (selected pH values are shown) was analyzed in the melting ((a) and (b)) and kinetic CD experiments (c). In the melting experiments, VLDL solutions were heated at a rate of 11°C/h. Changes in turbidity (a) and circular dichroism (b) were monitored at 320 nm for increase in the particle size upon lipoprotein fusion and coalescence into droplets (a) and lipoprotein rupture and repacking of apolar lipids in droplets (b). In temperature-jump experiments (c), VLDL heat denaturation was triggered at time by a rapid increase in temperature from 25 to 80°C, and the denaturation time course was monitored by turbidity at 220 nm.
