Lipid Extraction and Distribution Studies of Egg Yolk Lipoproteins

Abstract

I'he three lipoproteins of egg yolk, a-and p-lipovitellin and the low-density fraction (LDF), have been isolated and their lipid compositions determined. a-and p-lipovitellin comprise 22 to 2670 lipid, of which 6 l y O is phospholipid, .35(,% is triglyceride, and 4y0 is cholesterol and its esters. L D F contains about 89(y0 lipid having 27y0 phospholipid, 69y0 triglyceride, and 4y0 cholesterol and cholesterol esters. The phospholipids of the three lipoproteins are similar, i.e., 74'% lecithins, 18% cephalins, and 870 minor phospholipids. The fatty acid coinpositiolls of the neutral lipids, lecithins, and cephalins of the a-and p-lipovitellins were also similar, with only minor differences. Gentle extraction of the L D F solutions with ethyl ether readily removes about 85y0 of the total lipid and 55Yo of the phospholipid, while subsequent changes are slow. 'I'he lipoprotein residue contains 5270 lipid which is mostly phospholipid; \\,hen the residual ether is removed, five sedi~nenting components are observed in the ultracentrifuge. 1Issued as N.R.C. No. 7144. Can. J. Biochem. Physiol. Downloaded from www.nrcresearchpress.com by STOCKHOLMS UNIVERSITET on 08/07/15 For personal use only.

Effect of Egg Yolk on Cryopreservation of Rhesus Monkey Ejaculated and Epididymal Sperm

“…Because LDL consists of 86%–89% lipids and 12.5% proteins (Martin et al, 1963), lipids have been the main focus for the study of the protective role of egg yolk (eg, Purdy and Graham, 2004; Ricker et al, 2006). However, besides egg yolk, other additives such as skimmed milk, soybean proteins, and bovine serum albumin (Stoss and Holtz, 1983; Foote et al, 2002) have also been used successfully in sperm cryopreservation as membrane stabilizers.…”

Gelation of Frozen-Defrosted Egg Yolk as Affected by Selected Additives: Viscosity and Electrophoretic Findings

“…Powrie et al (1963) demonstrated that in crude lipovitellin preparations, proteins form complexes on freezing and thawing. Martin et al (1963) believed that a-and /3-lipovitellin have a structural integrity approaching that of a protein molecule. Burley (1963) suggested that in the lipovitellins, the proteins and lipids are combined in a structure that is flexible enough to accommodate large amounts of certain other substances and that the process of expansion assists aggregation.…”

The Influence of Storage of Shell Eggs Produced by Hens Fed Crude Cottonseed Oil on the Very Low Density Lipoproteins Isolated From These Eggs

“…The egg yolk very low density lipoproteins were prepared from freshly laid eggs and from eggs which had been kept in cold storage for 6 months, using the procedure of Martin et al (1963) as modified by Evans et al (1968). Fresh preparations of the egg yolk very low density lipoproteins were made for each study.…”