title: Pregnancy-associated plasma protein A: purification under mild conditions, peptide mapping and tests for possible interactions with trypsin, plasmin and complement.
abstract: 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.
mesh_terms: D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003168:Complement Fixation Tests; D003165:Complement System Proteins / Q000378:metabolism*; D003488:Cyanogen Bromide / Q000494:pharmacology; D005341:Fibrinolysin / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D011257:Pregnancy Proteins / Q000302:isolation & purification*; D011266:Pregnancy-Associated Plasma Protein-A / Q000302:isolation & purification* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000032:analysis
chemical_list: D010446:Peptide Fragments; D011257:Pregnancy Proteins; D000511:alpha-Macroglobulins; D003165:Complement System Proteins; D014357:Trypsin; D005341:Fibrinolysin; D011266:Pregnancy-Associated Plasma Protein-A; D003488:Cyanogen Bromide