Human Plasma Very Low-Density Lipoproteins Are Stabilized by Electrostatic Interactions and Destabilized by Acidic pH
Figure 6
Kinetic analysis of the effects of Na phosphate on VLDL stability. Thermal denaturation of VLDL (0.1 mg/mL protein, 5–25 mM Na phosphate as indicated, pH 7.6) was triggered in temperature-jumps from 25°C to larger constant values of 70–95°C. The time course of denaturation was monitored by turbidity at 220 nm, V 220(t). (a) Representative data recorded in T-jumps to 85°C; Na phosphate concentrations are indicated. (b) Arrhenius analysis of the T-jump data recorded in 5 mM or in 25 mM Na phosphate. Solid lines show data fitting by linear functions; the slopes of these functions correspond to the activation energy (enthalpy) of VLDL denaturation. Linear extrapolation of the Arrhenius plots to 37°C suggests that VLDL stability decreases by about 3 kcal/mol upon increasing Na phosphate concentration from 5 to 25 mM (double arrow).
