SEPARATION AND PROPERTIES OF PIG-SERUM LIPOPROTEINS

Abstract

Pig serum contained three major classes of lipoproteins resembling the very low density (VLDL), low density (LDL), and high density lipoproteins (HDL) found in human serum but in smaller amounts. The LDL class had two clearly resolved components (LDL1and LDL2) that were separated by differential centrifugation at solvent densities of 1.060 and 1.090. Heterogeneity in density was evident in all fractions, especially in those of highest lipid content. Average molecular weights and lipid contents of the isolated fractions were: VLDL, 17 × 106and 90%; LDL1, 3 × 106and 79%; LDL2, 2 × 106and 72%; and HDL, 0.25 × 106and 51%. Apart from small differences in proportion, the lipoproteins in the pooled samples collected over an 18-month period were quite similar although more extensive measurements may reveal differences. The presence of these distinct and separable lipoprotein fractions suggest structural differences worthy of further study.