出版社：American Society for Biochemistry and Molecular Biology
摘要：Delipidation by ethanol-diethyl ether at -10°C of human serum high-density lipoprotein (HDL, d 1.063-1.21) or of its subclasses HDL2 (d 1.063-1.120) and HDL3 (d 1.120-1.21), yielded proteins-αP, αP2, and αP3-containing 3% phospholipid (largely lecithin) and 3.3% carbohydrate (glucosamine: l -fucose: d -galactose, d -mannose: sialic acid, 1.00:41:0.56:0.31). Solubility data and analytical ultracentrifugal analyses indicated that, upon lipid removal, HDL protein aggregates readily; the aggregation is dependent upon pH and ionic strength of the solvent medium. Subunits of 21,000 mol wt were obtained by acetylation or addition of sodium dodecyl sulfate (SDS). HDL and αP elicited in the rabbit a similar immunological response. By agar gel immunoelectrophoresis both anti-HDL and anti-αP sera detected a major and two minor antigenic determinants in HDL, HDL3, αP, αp2, and αP3. HDL2, antigenically homogeneous, gave an immunoelectrophoretic pattern of HDL3 upon mixing with αP. αP, αP2 and αP3 exhibited a single antigenic determinant after treatment with SDS (0.5 m ) or upon acetylation. Native or delipidated forms of HDL, HDL2, and HDL3 were separated by vertical starch gel electrophoresis into several components, which showed identical reactions against anti-HDL or anti-αP sera. The data suggest that ( a ) the proteins of HDL, HDL2, and HDL3 are made of subunits, probably identical, of an average molecular weight of 21,000; ( b ) the difference in antigenic behavior between HDL2 and HDL3 is due to the presence in the latter of a lipid-poor protein; ( c ) antigenic polymorphism of αP is probably related to the presence in solution of monomeric and polymeric forms having different reactivity against anti-HDL and anti-αP sera.
关键词：serum ; high density lipoprotein ; delipidation ; carbohydrate content ; solubility ; amino acid analysis ; ultracentrifugal properties ; immunoelectrophoresis ; starch gel immunoelectrophoresis ; protein subunits
