THE EFFECT OF TEMPERATURE AND CONCENTRATION OF LDL AND HDL CHOLESTERYL ESTERS AND LIPOPROTEIN DEFICIENT SERUM ON THE CHOLESTERYL ESTER TRANSFER-REACTION IN-VITRO

We studied the effect of temperature, concentration of low-density (LDL) and high-density lipoprotein (HDL) cholesteryl esters, and the concentration of human lipoprotein deficient serum (LPDS, a source of cholesteryl ester transfer activity) on the fluxes of cholesteryl esters between human LDL and HDL in vitro. Incubation temperatures above 37 degrees C resulted in an increase of the fluxes, and a six-fold increase was observed at 55 degrees C. Decreasing the temperature had the opposite effect, and no transfer activity was measured below 10 degrees C. Increasing the concentration of LPDS without changing the concentration of LDL and HDL resulted in a linear increase of the fluxes. Increasing the concentration of LDL and HDL cholesteryl esters without changing the concentration of LPDS resulted in a nonlinear increase of the fluxes, and the results could be described by a Lineweaver-Burk plot. When both the concentration of LPDS and HDL and LDL cholesteryl esters were increased in the same proportions, the fluxes increased more than proportionally.