Lipid composition and cholesterol esterification in serum lipoprotein fraction of the horse, Equus caballus

Abstract

1. 1. Changes in lipid components of lipoproteins during incubation of horse serum at 37°C were investigated. In non-incubated serum, cholesterol and lecithin existed predominantly in α-lipoprotein or in high-density lipoprotein (HDL). Lysolecithin was mainly associated with the fraction with density above 1.21. 2. 2. When serum was separated into α- and β-lipoproteins by the heparin precipitation method after 1 hr incubation, the decrease in α-lipoprotein free cholesterol and lecithin was about four times that in β-lipoprotein counterparts. 3. 3. When serum lipoproteins were separated by ultracentrifugation, the decrease in each lipoprotein free cholesterol was closely paralleled with that in lecithin. 4. 4. HDL appeared to be a preferential substrate for the lecithin: cholesterol acyltransferase reaction. 5. 5. Disc electrophoretic patterns indicated significant differences in the compositions of horse serum lipoproteins from those of human and rat.