PURIFICATION AND CHARACTERIZATION OF 2 NEW SOLUBLE PLACENTAL TISSUE PROTEINS (PP13 AND PP17)

  • 1 January 1983
    • journal article
    • research article
    • Vol. 4  (5) , 343-350
Abstract
Two new soluble human placental tissue proteins (PP13 and PP17) were isolated and characterized. PP13 has an electrophoretic mobility the same as that of albumin, an isoelectric point in the range 4.7-4.8 and a sedimentation coefficient of 3.1S. Its MW was 30,000. PP13 appears to be composed of 2 identical subunits which are held together by disulfide bonds. PP17 has an electrophoretic mobility in between the .beta.1- and .alpha.2-globulins, an isoelectric point in the range 5.2-5.3 and a sedimentation coefficient of 2.7S. Its MW was determined to be 30,300 by ultracentrifugation and 38,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. PP17 apparently consists of a single peptide chain. The amino acid and carbohydrate compositions of these proteins were determined. Immunochemical methods were used to detect and quantitate the new proteins in extracts of placental and other human tissues and in body fluids. From 1 human term placenta an average of 3.7 mg PP13 and 2.5 mg PP17 could be extracted. In concentrated extracts of other human tissues and in body fluids, these proteins could not be detected, at least not in concentrations higher than 1 mg/dl. The immunohistochemical localization of these proteins and measurement of their concentrations in body fluids by sensitive radioimmunoassays are presently under investigation.