Abstracts Biological Sciences

Aspects of the chemical structure and metabolism of serum lipoproteins

by Anita I. Eckhaus

The VLDL of both human and rat sera can be dissociated by heparin into an a- and a β-Iipoprotein-containing component of reproducible composition. The heparin precipitable β-containing component of human and rat VLDL contains more than 90% of the triglycerides and cholesterol of that fraction, consistent with the role of the β-lipoproteins as the main triglyceride and cholesterol carriers in the circulation. The heparin soluble a-containing component contains a higher phospholipid to protein ratio than that of any of the other serum lipoprotein fractions, suggesting that it may contain a peptide with high affinity for phospholipids such as the "C" protein, known to be present in human VLDL. Only about 10% of the protein of human and rat VLDL was found in the heparin soluble fraction, while 90% was recovered in the heparin precipitable fraction. The lipid composition of the β-containing component of the VLDL does not resemble that of the β-protein of LDL, nor does the a-containing component of the VLDL resemble the a-protein of the HDL in this respect.