Pregnancy associated plasma protein-A: interaction with heparin in crossed affinity immunoelectrophoresis

A specific interaction between pregnancy associated plasma protein A- (PAPP A) and heparin has been demonstrated using heparin affinity crossed immunoelectrophoresis applied to late pregnancy serum. The presence of heparin in the first dimensional gel accelerated the anodic migration of six serum proteins with beta electrophoretic mobility and one protein in the alpha mobile region. Two of the six beta mobile proteins were identified as antithrombin III and beta lipoprotein, the alpha mobile protein being PAPP-A. The migration distance of other proteins originating in the placenta (pregnancy specific beta, glycoprotein), fetus (alpha-fetoprotein), leucocytes (pregnancy zone protein), or maternal liver (alpha, antitrypsin alpha 2 macroglobulin) was not altered. The interaction of PAPP-A with heparin was therefore independent of molecular size, charge, and site of origin indicating a specific high affinity interaction between PAPP-A and heparin. There results indicate that PAPP-A may be involved locally with the coagulation system in the maintenance of placental circulation.