STUDIES ON THE PROTEIN-COMPOSITION OF HUMAN-SERUM VERY LOW-DENSITY LIPOPROTEINS - DEMONSTRATION OF THE BETA-2-GLYCOPROTEIN-I

Human serum VLDL isolated by poly-anion precipitation and ultracentrifugation have been delipidated with ethanol/diethyl ether. By electrophoresis in 10% polyacrylamide gels containing 8m urea, we found a protein which comigrated with apolipoprotein E. This protein was purified by column chromatography and turned out to be identical with β2-giycoprotein-I, the serum factor which is necessary for the precipitation of triglyceride-rich lipoproteins with sodium decyl sulfate or sodium dodecyl sulfate. Upon analytical isoelectric focusing, β2-glycoprotein-! gave four major bands in the pH region 5.7-6.6. All four bands gave an immunochemical reaction of identity with a monospecific antiserum. From its unique amino acid composition we conclude that β2-glycoprotein-I is distinct from all apolipoproteins described previously in the literature. © 1979 Walter de Gruyter & Co.