Journal of Lipid Research, Vol. 9, 180-186, March 1968
Copyright © 1968 by Lipid Research, Inc.

The surface coat of chylomicrons: lipid chemistry

D. B. Zilversmit

Graduate School of Nutrition and the Section of Biochemistry and Molecular Biology, Division of Biological Sciences, Cornell University, Ithaca, New York 14850

Chylomicrons from the thoracic duct lymph of dogs fed corn oil were isolated by centrifugation and disrupted by either freezing and thawing or rotary evaporation and rehydration. A pellet, representing the surface coat, was isolated by centrifugation. Pellets isolated by freezing and thawing contained a higher percentage of saturated triglycerides than pellets isolated by rotary evaporation; the presence of saturated triglyceride in the pellet was probably an artifact of the preparation of the surface coat material at low temperature.

Exchange of free cholesterol between surface and core lipid of chylomicrons was complete within 1 hr. The percentage of cholesterol in pellets of surface material isolated by freezing and thawing was about twice that found for pellets after rotary evaporation at 25-40°C. Cholesteryl ester was not present in the surface lipid and that present in the core lipid did not exchange with serum lipoprotein cholesteryl ester.

For phosphatidyl choline, the percentage of linoleic acid in lymph chylomicrons was markedly higher than that in clear lymph or plasma, while the percentage of arachidonic acid was lower. Sphingomyelin of lymph chylomicrons was characterized by very high levels of 16:0 and relatively small percentages of very long-chain fatty acids as compared with clear lymph or plasma.

The data are consistent with the view that in lymph chylomicrons: (a) cholesteryl esters are dissolved in a core of triglycerides which contain fatty acids derived primarily from dietary fatty acids, (b) free cholesterol is partitioned between core and surface and is freely exchangeable between the two, (c) the phospholipid fractions are present on the surface and are intracellular in origin.

Supplementary key words chylomicrons • core and surface lipid composition • fatty acids • dog • lymph • plasma

Submitted on July 10, 1967
Accepted on November 6, 1967

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				A. Nilsson and R.-D. Duan Absorption and lipoprotein transport of sphingomyelin J. Lipid Res., January 1, 2006; 47(1): 154 - 171. [Abstract] [Full Text] [PDF]