[Isolation and characterization of the placental proteil pp1 (author's transl)]

The purification and characterization of the placental protein PP1 is described. The protein has been isolated from an aqueous extract of human term placentae using salt and ethanol fractionation procedures, gel filtration, preparative zone electrophoresis and chromatography on hydroxylapatite. PP1 sediments with 8.4 S and has a molecular weight of 160,000 daltons; it is composed of apparently four identical subunits, which have a molecular weight of 40,000 +/- 2000 daltons and are held together by non-covalent bonds. PP1 is a glycoprotein with a carbohydrate content of 2.7% and has the electrophoretic mobility of an alpha1-globulin. Immunochemical methods were used for the detection and quantitative determination of the protein. PP1 is not found in normal plasma or in erythrocytes; neither could it be detected in sera from pregnant women nor in sera from patients suffering from malignant diseases. PP1 is a tissue protein, but not specific for the placenta; it is also found in other human tissues. The average amount of PP1 extracted from one human term placenta was determined to be around 3 mg. Immunogluorescent studies revealed that the protein is located in the cytoplasma of the syncytium as well as in the stroma of the villi.