Characterization of very-low-density lipoproteins isolated from baboons, and fractionated using heparin-Sepharose chromatography.
Plasma very-low-density lipoproteins (VLDL) (d less than 1.006 g/ml) were purified from baboons by repeated ultracentrifugation. The weight composition of VLDL purified from these animals was 59% triacylglycerol, 17% phospholipid, 13% cholesterol plus cholesteryl esters, and 11% protein. When purified VLDL was fractionated using heparin-Sepharose chromatography, an average of 33% of the total recovered proteins were unbound in a saline solution, and 67% (range, 31 to 92%) were bound by the column, but could be eluted with 3 M NaCl. Recoveries of starting protein and the major classes of lipids in the two fractions were 70-80%. The two fractions differed in both apolipoprotein and lipid compositions. Analysis of sodium dodecyl sulfate-treated apolipoproteins using 3-21.5% acrylamide gradient gel electrophoresis indicated that both VLDL fractions contained apolipoprotein B, but only the bound fraction possessed significant amounts of apolipoprotein E. On a weight percent basis, the apolipoprotein-E-rich (bound) VLDL fraction contained significantly more cholesterol and cholesteryl esters (P less than 0.001) and less phospholipids (P less than 0.005) compared to the apolipoprotein E-poor (unbound) VLDL. Apolipoprotein-E-poor VLDL had shorter retention times than E-rich VLDL upon gel filtration chromatography, suggesting a larger size. There was no significant correlation between plasma levels of apolipoprotein-E-poor VLDL and levels of apolipoprotein B. These results demonstrate that baboons possess VLDL which can be separated into apolipoprotein-E-poor and E-rich fractions and these fractions differ in protein and lipid composition and in size.
Rainwater
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Departments of Genetics, Southwest Foundation for Biomedical Research, San Antonio, TX 78284.
Kushwaha
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D000818:Animals; D001055:Apolipoproteins B / Q000097:blood; D001057:Apolipoproteins E / Q000097:blood; D005591:Chemical Fractionation; D002784:Cholesterol / Q000032:analysis; D002845:Chromatography; D005260:Female; D008079:Lipoproteins, VLDL / Q000097:blood*; D008297:Male; D010215:Papio; D010743:Phospholipids / Q000032:analysis; D011506:Proteins / Q000032:analysis; D014280:Triglycerides / Q000032:analysis; D014461:Ultracentrifugation
D001055:Apolipoproteins B; D001057:Apolipoproteins E; D008079:Lipoproteins, VLDL; D010743:Phospholipids; D011506:Proteins; D014280:Triglycerides; D002784:Cholesterol