Johnson P, Muirhead R A, Deegan T
Ann Clin Biochem. 1981 Sep;18(Pt 5):308-13. doi: 10.1177/000456328101800508.
By use of an electroimmunoassay, concentrations of A-apoproteins were estimated in serum and in corresponding apoprotein fractions isolated by ultracentrifugation. These values were compared with high-density lipoprotein concentrations determined by analytical ultracentrifugation. Concentrations of A-apoproteins estimated in serum were considerably higher than in isolated high-density lipoprotein fractions. These discrepancies could not be accounted for entirely by material losses into other fractions during ultracentrifugal fractionation. No comparable differences in apoprotein-B concentrations were observed during the ultracentrifugal separation of low-density lipoprotein. Concentrations of A-apoproteins estimated in the residual serum after precipitation of low-density lipoproteins by heparin and manganous ions were also lower than in the corresponding whole sera. The discrepancies persisted after treatment of serum and isolated fractions with tetramethylurea, urea (9 mol/l), and by heating at 52 degrees C for 3 hours. It is considered that separation by ultracentrifugation induces subtle alterations in the surface structure of the lipoprotein species which give rise to changes in immunoreactivity.
通过使用电免疫测定法，对血清中以及通过超速离心分离得到的相应载脂蛋白组分中的A类载脂蛋白浓度进行了估算。将这些值与通过分析超速离心法测定的高密度脂蛋白浓度进行了比较。血清中估算的A类载脂蛋白浓度明显高于分离得到的高密度脂蛋白组分中的浓度。这些差异不能完全归因于超速离心分级分离过程中其他组分的物质损失。在低密度脂蛋白的超速离心分离过程中，未观察到载脂蛋白B浓度有类似差异。用肝素和锰离子沉淀低密度脂蛋白后，残余血清中估算的A类载脂蛋白浓度也低于相应的全血清。在用四甲基脲、尿素（9摩尔/升）处理血清和分离组分以及在52℃加热3小时后，差异仍然存在。据认为，超速离心分离会引起脂蛋白种类表面结构的细微改变，从而导致免疫反应性的变化。
