[Isolation and characterization of a new tissue protein (pp7) from human placentae (author's transl)].

The isolation and characterization of a new tissue protein (PP7) from human placentae is described. The placental protein PP7 is not specific for the placenta; it is found in relative high concentrations in other human tissues as well. Trace amounts of PP7 occur in erythrocytes, too. In sera this protein could not be detected with the gel diffusion test of Ouchterlony nor with the electroimmunoassay technique. PP7 has a molecular weight of around 40,000 daltons and is composed of two identical subunits which are non-covalently linked. In the ultracentrifuge PP7 sediments with 3.5 S. The isoelectric point was found to be 4.9. Electrophoretically the protein migrates in the range between alpha 2 and beta1-globulins. PP7 is a glycoprotein; its carbohydrate content amounts to 5.4% (hexoses 3.0%, Hexosamine 1.2%, Fucose 0.2%, sialic acid 1.0%). The amino acid composition of the protein is reported, too.