Jones G R, Davey M W, Sinosich M, Grudzinskas J G
Clin Chim Acta. 1981 Feb 19;110(1):65-70. doi: 10.1016/0009-8981(81)90301-6.
Levels of placental protein 5 (PP5) in paired serum and plasma samples obtained during the second half of pregnancy were measured by radioimmunoassay. The apparent level of PP5 was significantly higher in serum than in heparin-derived plasma. The addition of heparin to late pregnancy serum resulted in a dose-dependent decrease in the apparent PP5 concentrations, the maximal effect occurring at heparin concentrations greater than 4 U/ml. The same phenomenon was observed using purified PP5 and placental homogenate. The effect of heparin was readily reversed by the addition of protamine sulphate. The specificity of the interaction between heparin and PP5 was demonstrated by affinity chromatography with heparin as the ligand. The functional significance of these results are discussed in relation to observations on other placental proteins and proteins with affinity to heparin.
采用放射免疫分析法测定妊娠后半期采集的配对血清和血浆样本中胎盘蛋白5（PP5）的水平。血清中PP5的表观水平显著高于肝素衍生血浆中的水平。向妊娠晚期血清中添加肝素会导致表观PP5浓度呈剂量依赖性降低，在肝素浓度大于4 U/ml时出现最大效应。使用纯化的PP5和胎盘匀浆也观察到了相同的现象。添加硫酸鱼精蛋白可使肝素的作用轻易逆转。以肝素为配体的亲和层析证明了肝素与PP5之间相互作用的特异性。结合对其他胎盘蛋白和与肝素有亲和力的蛋白的观察结果，讨论了这些结果的功能意义。
