Influence of the electrostatic charge of lipoprotein particles on the activity of the human plasma phospholipid transfer protein

The aim of the present study was to determine the effect of the electrostatic charge of lipoproteins on the phospholipid transfer activity of the plasma phospholipid transfer protein (PLTP). Progressive decreases in the PLTP-mediated phospholipid transfer rates were observed when the surface potential of isolated high density lipoproteins (HDL) was either reduced from -11.7 mV down to -15.7 mV by succinylation of apolipoprotein lysyl residues, or increased from -11.6 mV up to -10.9 mV by replacing apolipoprotein (apo) A-I by apoA-II. When succinylated low density lipoprotein (LDL) series with surface potentials ranging between -4.3 mV and -14.3 mV were used, successive increase and decrease in phospholipid transfer rates were observed along the electronegativity scale. When various plasma HDL subfractions with surface potentials ranging from -10.5 mV to -12.5 mV were separated by anion exchange chromatography, PLTP-mediated phospholipid transfer activity increased progressively with HDL electronegativity until maximal lipid transfer rates were reached for a mean HDL surface potential of -11.6 mV. As the electronegativity of plasma HDL subfractions kept increasing beyond the optimal value, a progressive decrease in PLTP activity was observed. Striking parallelism between cholesteryl ester transfer protein (CETP) and PLTP transfer activity curves obtained with each HDL series were noted, and the optimal HDL surface potential values were remarkably similar, approximating -11.6 mV in all the experiments. With isolated plasma LDL subfractions with surface potentials ranging from -3.5 mV to -5.0 mV, a linear rise in PLTP activity was observed. In conclusion, data of the present study indicate that, like CETP, the activity of PLTP is influenced by electrostatic interactions with lipoproteins