Isolation and characterization of two membrane-associated placental tissue proteins

Two membrane associated placental tissue proteins (PP4 and MP1) have been isolated and characterized. Both proteins are found in the soluble as well as solubilized protein fractions of the human placenta and thus appear to be at least partly associated with placental membranes. PP4 has a molecular weight of 35000 and apparently consists of a single peptide chain. It has an electrophoretic mobility in between the alpha 1- and alpha 2-globulins, an isoelectric point of 4.85 and a sedimentation coefficient of 3.3 S. The carbohydrate content of PP4 amounts to 2.4%. MP1 was isolated from placental protein fractions solubilized with Triton X-100. It has a molecular weight of around 18000 and appears to be composed of two identical subunits which are non-covalently linked. MP1 was found to have an electrophoretic mobility in between the alpha 2- and beta 1-globulins, an isoelectric point of 4.75 and a sedimentation coefficient of 6.65 S. MP1 is a glycoprotein which contains 9.6% carbohydrates. Immunochemical methods were used to detect and quantitate PP4 and MP1 in extracts of placentae and other human tissues. MP1 appears to be specific to the placenta, whereas PP4 was found to occur also in certain other human tissues. The diagnostic significance of detection and measurement of these proteins in tissues and body fluids is presently under investigation.

Isolation and characterization of four new placental tissue proteins (PP18, PP19, PP20, PP21)

Four new soluble placental tissue proteins (PP18, PP19, PP20, PP21) have been isolated to purity from saline extracts of human term placentas. Two of the new proteins appear to be partly associated with placental membranes; they also could be detected in placental protein fractions obtained by extracting the insoluble part of the placental tissue with solubilizing agents after the soluble material had been removed by washing with saline. The new placental proteins were characterized by their physical properties as well as by their carbohydrate and aminoacid compositions. Specific antisera to the new proteins were obtained by immunizing animals with the corresponding purified proteins. They were used to detect and quantitate the new proteins in extracts of placentas and other human tissues by immunochemical methods. From one human term placenta an average of 2 mg PP18, 90 mg PP19, 0.5 mg PP20, and around 7 mg PP21 could be extracted. None of these new proteins is specific to the placenta; they also were found to occur in extracts of certain other human tissues. The immunohistochemical localization of these proteins as well as measurement of their concentrations in body fluids by sensitive radioimmunoassays are presently under investigation.

Characterization of P4, a natural inhibitor of cellular cytotoxicity reaction in pregnant women

A factor present in the serum of pregnant women is able to inhibit nonspecifically a cellular cytotoxicity reaction. This glycoprotein called P4, is an alpha-globulin whose molecular weight is 200,000 daltons bound to albumin. Its isoelectric point is 4.1. By its various characteristics, P4 seems different from other proteins so far described.

A placental polypeptide activator of a membranous protein kinase and its relation to histone 1

Crude transforming growth factor preparations of placenta contain a polypeptide that is required for the activity of a protein kinase that has been purified from plasma membrane preparations of Ehrlich ascites tumor cells. The kinase activator has been separated from transforming growth factor beta by reversed-phase HPLC and affinity chromatography. Like the transforming growth factor, it is heat stable and trypsin labile, but it is not inactivated by dithiothreitol. In sodium dodecyl sulfate/polyacrylamide gel electrophoresis the purified preparation shows a major double band at about 31,000 daltons. Comparisons of electrophoretic mobility, protein kinase stimulatory activity, and cross-reactivity with an antibody against histone 1 suggest that the placental activator is identical with histone 1.

[The purification of pregnancy specific beta 1-glycoprotein (SP1) from third trimester serum and the immunological identification of gamma-component of SP1]

This paper describes the SP1 purification procedures with high recovery from third trimester serum and the finding of a new SP1 antigen with gamma-mobility (tentatively called SP1-gamma). The serum was salted out at 40% saturation with ammonium sulfate and this was followed by Sephadex G-150, DEAE-cellulose, SP1-negative affinity chromatography and the mono-Q column of FPLC system. The anti-serum for the immunoadsorption techniques was made from the fractionated male serum. By these procedures, the final SP1 preparation was obtained in a yield of 16% and with a purity of 99%. The purified SP1 (SP1-beta) had beta-mobility and its molecular weight approximated 72,000 in SDS polyacryl-amide gel electrophoresis. The isoelectric points (pI) ranged between 3.80 to 4.55 using isoelectric focusing and the site at pI 4.15 was strongly stained. Another SP1, which passed through DEAE-cellulose with a low salt concentration, was detected in the gamma-region by means of immunoelectrophoresis using anti-SP1 serum. It was ascertained that the SP1-gamma was different from the SP1-beta treated with neuraminidase. The SP1-gamma precipitation fusing with SP1-beta could be observed even in pregnant serum by usual immunoelectrophoresis. The SP1-gamma preparation showed at least four pIs of 5.3, 5.5, 5.65 and 5.8.

Comparison of three methods for investigating placental protein 12(PP12)-like immunoreactive substance from preovulatory follicular fluid and purified PP12 from human placenta

Placental protein 12(PP12)-like immunoreactive fraction of preovulatory follicular fluid from Sephadex G-100 and purified placental PP12 were subjected to reverse phase high performance liquid chromatography (HPLC). The elution was carried out with acetonitrile gradient. PP12-like immunoreactivity of both samples had the same retention time. This fraction of follicular fluid from HPLC and placental PP12 were then run on a sodium dodecyl sulfate-polyacrylamide gel and transferred electrophoretically to a nitrocellulose (NC) sheet. Protein bands on the NC sheet were then detected immunologically with anti-PP12 antisera. After visualising the bands which had reacted with antisera it was obvious that PP12-like immunoreactive substance from follicular fluid and from placenta had an electrophoretic mobility corresponding to the same molecular mass.

Pregnancy-associated plasma protein A: purification under mild conditions, peptide mapping and tests for possible interactions with trypsin, plasmin and complement

Pregnancy-associated plasma protein A (PAPP-A) has been obtained in an enriched state under mild conditions of purification involving cibacron blue dye-ligand chromatography, negative antibody-affinity chromatography and gel filtration. The product was a mixture of PAPP-A and alpha-2-macroglobulin (alpha 2M). The ability of these proteins to bind 125I-trypsin and 125I-plasmin was studied. In contrast to previous studies by others, there was no evidence that PAPP-A could bind either protease. It is pointed out that protease-inhibitory activity in samples of PAPP-A can be due to the presence of very small amounts of contaminating alpha 2M in the preparations of PAPP-A. In further experiments PAPP-A did not inhibit the complement-induced lysis of sensitized red cells. Finally, cyanogen bromide peptide mapping experiments failed to yield evidence of structural homologies between PAPP-A and alpha 2M.

Inhibitors of platelet aggregation and blood coagulation isolated from the human placenta

We identified 2 potent proteins with inhibiting activities of platelet aggregation and blood coagulation from the human placenta. Ultracentrifugation of placental homogenate showed that these proteins are incorporated in the microsomal membrane. These proteins were solubilized in Triton X-100 by means of sonication. The inhibitors were purified by several steps of chromatography and gel filtration in a single band on polyacrylamide gel electrophoresis, having molecular weights of 450 000 and 45 000. The aggregation inhibitor was different from inhibitors reported previously such as phosphatase and prostacyclin-like substance. The coagulation inhibitor was capable of inactivating tissue thromboplastin.

Purification and properties of a mammary-uterine-pituitary tumor cell growth factor from pregnant sheep uterus

A mammary-uterine-pituitary tumor cell growth factor has been purified from lyophilized powders of pregnant sheep uteri by a five-step procedure. Uterine-derived growth factor (UDGF) was extracted from the powders with 0.1 M acetic acid, heated at 95 degrees C, and further purified by sulfopropyl-Sephadex C-25, Sephadex G-50, and carboxymethyl-Sephadex C-25 chromatography. From 500 g of uterine powder, 40 to 50 mg of UDGF can be isolated at an overall yield of 33%. The degree of homogeneity of the final preparations was estimated by 8 M urea, 0.1% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE), and by PAGE under nondissociating conditions at either pH 8.5 or 4.5. In all PAGE experiments, the purified UDGF preparation showed a single Coomassie blue-stained band that directly corresponded to the only area of elution of UDGF activity from duplicate unstained gels. Molecular sieve high performance liquid chromatography HPLC, reverse phase HPLC on an octylsilyl (C8) column, and hydrophobic chromatography on octyl-Sepharose CL-4B all confirm a similar degree (i.e. greater than 90%) of homogeneity. The Mr of UDGF estimated by urea/sodium dodecyl sulfate-PAGE was 4200 +/- 500 and, by molecular sieve HPLC, 6200 +/- 1000. The isoelectric point of UDGF was estimated as pI = 7.3. The UDGF isolated showed marked cell-type specificity for established cell lines that were derived from estrogen-responsive tumors; purified sheep UDGF was mitogenic for MTW9/PL rat mammary tumor cells (at 10(-10) to 10(-9) M concentrations) while showing no mitogenic activity toward normal rat diploid fibroblasts. UDGF also promoted growth of uterine-derived tumor cells and the GH3/C14 rat pituitary line. Measuring growth as an increase in cell number, UDGF supported the logarithmic growth of the MTW9/PL rat mammary tumor cells over 6 days; other known hormones and growth factors were not able to substitute for the UDGF mitogenic action on MTW9/PL cells. It is concluded that a rapid, high-yield method of purification of a new uterine-derived growth factor activity has been developed.

[Isolation and purification of specific proteins, forming during endometrium differentiation into decidual tissue]

Using analytical PAAG-electrophoresis two specific proteins, D1 and D2, were found in decidual tissue of pregnant women (6-12 weeks). These proteins were isolated and purified by means of ammonium sulfate saturation, chromatography on Sepharose 6B and ion exchange chromatography on DEAE 52 cellulose. The degree of purification of both D1 and D2 proteins was 100% and 81%, respectively. The both proteins were free of DNA, RNA and polysaccharides. The pI values of D1 and D2 proteins were at pH 5.6-6.0. According to gel electrophoresis on PAA-SDS-Na and gel filtration on Sepharose 6B, molecular weight of D1 protein was about 50,000-55,000 and of D2 protein--150,000-160,000 and 300,000-320,000, respectively. The specific decidual proteins D1 and D2 appear to be distinct from the so-called "pregnancy proteins" described previously.

[Change in the activity of the microsomal system of liver oxidation in rabbits in experimental atherosclerosis]

Oxidizing ability of rabbit liver tissue was studied in experimental atheromatosis, while the functional activity of microsomal enzymatic system was evaluated by content of cytochromes P-450 and b5 as well by estimation of the reductase activity and the rates of oxidation of aniline, dimethylalanine, p-nitroanisole and amidopyrine with NADN and NADPH as cosubstrates. In rabbits with atheromatous impairment of aorta all the patterns studied were decreased by 30-70%. Severity of the aorta impairment correlated directly with the liver tissue deterioration and the rate of alteration in activity of the microsomal system oxidation constituents. The most distinct changes were found in NADPH-dependent reactions and in cytochrome P-450. The data obtained suggest that experimental atheromatosis of rabbits, produced after cholesterol loading, is responsible for distinct impairment of liver microsomal enzymatic system. The most profound alterations were observed in the components involved in the cholesterol-7 alpha-hydroxylase reaction.

[Tumor and fetus associated proteins--with special reference to alpha-proteins isolated and purified from rat placenta]

High molecular alpha-protein was isolated from rat placenta and purified with ammonium sulfate fraction and by DEAE cellulose column chromatography and Sephadex G-200 column chromatography, its physicochemical properties were elucidated. The serum alpha-protein levels were determined in pregnant rats, neonatal rats and tumor bearing rats according to single radial immunodiffusion. This protein was found to have a molecular weight of 750,000, an isoelectric point of 4.9 and E 1%1cm (280nm) of 9.0, showing mobility at position alpha 2 on immunoelectrophoresis. A small amount (24 +/- 8 micrograms/ml) was found in the serum of normal adult rat. In pregnant rats the serum level began to increase on the 10th day of pregnancy, reached its maximum (524 +/- 194 micrograms/ml) on the day of delivery, and thereafter gradually decreased. In neonatal rats the serum level reached its maximum (2104 +/- 446 micrograms/ml) on the 1st day after birth and thereafter gradually decreased. In the fetus the serum level was 3 to 4 times higher than that of the maternal rat. The protein levels were increased in the serum and ascites of some tumor bearing rats. These results suggest that this protein is related to the tumor and fetus.

[Use of Wheat Germ Lectin-Sepharose for isolating pregnancy-specific protein]

Specific pregnancy protein was obtained from retroplacental blood serum by saline fractionation, affinity chromatography on Wheat germ Lectin-Sepharose, gel filtration on Sephadex G-200, hydrophobic chromatography on Phenyl-Sepharose, and ion exchange chromatography on DEAE-Sephacel. The purified preparation of specific pregnancy protein is highly suitable for preparing antisera and the development of immuno- and radioassays of the protein in question.

Pregnancy-associated alpha 2-macroglobulin - a new serum protein elevated in normal human pregnancy

A new pregnancy-associated serum protein has been isolated and characterised - pregnancy-associated alpha 2-macroglobulin (alpha 2-PAM). The native macromolecule has a molecular weight of 2.1 x 10(6) and a sedimentation coefficient of 19.6 S. This is comprised of 28 000 dalton subunits and contains 11% carbohydrate. alpha 2-PAM was found in normal male and female blood at a concentration of 25 micrograms/ml but no significant variation in this value was apparent in individuals followed over a 12 week period. The serum level can rise up to 16-fold during the first trimester of pregnancy and returns to normal levels within 8 weeks after delivery. Concentrations in contraceptive-steroid treated women, cord blood and breast milk were in the same range as normal adult sera while alpha 2-PAM could readily be detected in amniotic fluid at 8 micrograms/ml.

A method for the purification of placental protein 5 (PP5) from placental extracts

We describe a method for the preparation of purified PP5 suitable for use as a tracer ligand in RIA. The method is based on the observation that PP5 will bind to heparin and employs a heparin-Sepharose column as a key step in the procedure.

Comparative studies of pregnancy associated plasma protein-A and alpha 2-macroglobulin using metal chelate chromatography

Pregnancy Associated Plasma Protein-A (PAPP-A), shares many physicochemical and functional similarities with alpha-2-macroglobulin (alpha 2M). Comparative studies between these two proteins and various metal chelate Sepharoses have shown that both PAPP-A and alpha 2M bind to the copper and zinc, but not to the calcium, manganese or magnesium chelate gels. In addition to PAPP-A and alpha 2M, fibronectin and Pregnancy Zone Protein (PZP) were also found to bind to the copper and zinc chelate gels. Analysis of proteins bound to the zinc chelate Sepharose showed alpha 2M to have the highest affinity for the matrix, followed by PAPP-A and fibronectin, which coeluted, and then PZP. Following the zinc chelate chromatography minor qualitative changes were detected only in PAPP-A, but the eluted proteins retained in-vitro functional activity. By atomic absorption, PAPP-A, alpha 2M and fibronectin were found to contain zinc.

Identification of a factor blocking a cellular cytotoxicity reaction in pregnant serum

A blocking factor present in the serum of pregnant women is able to inhibit non-specifically a cellular cytotoxicity reaction. It is a glycoprotein, migrating in the alpha-globulin region with a molecular weight of about 210,000 daltons. Its absence from the serum of women with recurrent abortions could predict the outcome of pregnancy.

Characterization of an immune suppressor from transformed human trophoblastic JEG-3 cells

Cultured human choriocarcinoma JEG-3 cells secrete an immunosuppressor that inhibits lymphocyte proliferation stimulated by either an antigen or a mitogen. In this study, the immunosuppressive factor was characterized by three methods: ion-exchange and exclusion chromatography, partition in organic solvents, and thin-layer chromatography on silicic acid. This JEG-3 cell factor appeared to be a protein complex of about 150,000-200,000 Da that contained an immunologically active polar lipid. The structural and functional characteristics of JEG-3 cell immunosuppressor are similar if not identical to those of SIF, a suppressor lymphokine derived from T cells. These secretions from transformed trophoblastic cells may correspond to normal placental products or represent a function of malignant cells.

[Nephritogenic glycoprotein isolated from human placenta (methods of isolation from placenta]

In our experiments, we succeeded in obtaining from human placenta a substance comparable to human renal nephritogenic glycoprotein prepared from GBM (glomerular basement membrane). The procedure was quite similar to that for preparation from the kidney. At first, placental terminal villi were isolated by the successive use of three metal sieves. Then trophoblast basement membranes (TrBM) were isolated from placental terminal villi by ultrasonic disruption. Finally TrBM were made soluble by trypsin digestion, after which they were further digested by pronase. Ouchterlony gel diffusion demonstrated the existence of a common precipitin line between antiserum to human renal nephritogenic glycoprotein prepared from GBM and antiserum to the sample prepared from human placental TrBM, and human renal nephritogenic glycoprotein prepared from GBM and the sample prepared from human placental TrBM. The monosaccharide composition of the sample prepared from human placental TrBM was rich in glucose (glucose, galactose and mannoside in the ratio of 1.00 : 0.74 : 1.00), and the amino acid composition of the sample contained no collagenous components. As a result of fractionation of the sample prepared from human placental TrBM by Bio Gel P200 column chromatography, the activity of renal nephritogenic glycoprotein was found within the void fraction.

Purification of pregnancy-specific beta 1-glycoprotein with a monoclonal antibody immunoadsorbent

Hybrid cell lines secreting monoclonal antibodies against pregnancy-specific beta 1-glycoprotein (SP1) were produced by fusion of a mouse myeloma cell line with spleen cells from BALB/c mice immunized with purified placental SP1. The clones were further grown intraperitoneally in mice, and the ascites fluids contained anti-SP1 antibodies in high titers. One of the monoclonal antibodies was coupled to cyanogen-bromide-activated Sepharose and used for affinity chromatography of SP1 using late pregnancy serum as starting material. The purification of SP1 by means of immunoadsorption utilizing monoclonal antibodies offers remarkable advantages compared with the purification procedures used so far.

Interaction between heparin and human pregnancy-associated plasma protein A (PAPP-A): a simple purification procedure

Human pregnancy-associated plasma protein A (PAPP-A) binds to heparin-Sepharose. This affinity chromatography preceded by molecular sieve chromatography provides a simple two-step purification procedure of PAPP-A from late pregnancy plasma. One hundred percent of the applied PAPP-A was recovered, with more than 40% being electrophoretically homogeneous after the two procedures. The remaining PAPP-A could be purified by negative affinity chromatography on anti-total human serum immobilized on agarose.