title: [Purification and identification of pregnancy associated plasma protein A].
abstract: OBJECTIVE
  To purify pregnancy associated plasma protein A (PAPP-A) from the pregnancy serum using the methods of G200 gel filtration, reverse affinity chromatography and DEAE ion exchange.
  
  
  METHODS
  The male sera were purified by G200 gel filtration and injected into rabbits to obtain rabbit-anti-human antibodies. The antibodies were linked to CNBr-activated G25 gel to make the reverse affinity chromatography. The full-term pregnancy sera were collected and centrifuged, followed by G200 gel filtration, reverse affinity chromatography and DEAE ion exchange. ELISA and SDS-PAGE were performed to detect the activity and the purity of PAPP-A.
  
  
  RESULTS
  As detected by the double diffusion, the rabbit-anti-human antibodies were active in the dilution of 1:16, and were further used for purification of PAPP-A. The PAPP-A exited in the last peak with the pH3.0 elutriant by SPA, the first peak by G200 gel filtration, the peak with 0.1 mol/L PBS elutriant by the reverse affinity chromatography, and the peak with 0.45 mol/L NaCl elutriant by the DEAE ion exchange. The SDS-PAGE results indicated that the triple treatments of the pregnancy sera by G200 gel filtration, the reverse affinity chromatography and the DEAE ion exchange effectively enhanced purity of PAPP-A, with a single protein band shown by Western blot, whereas a single purification method produced dirty bands.
  
  
  CONCLUSIONS
  High purity PAPP-A has been obtained, ready for preparation of its monoclonal antibody. The study paves a way for development of PAPP-A based ELISA kits for clinical use.
authors.affiliation: Graduate School of Tianjin Medical University, Tianjin 300070, China. zengzhaowei-1@163.com
authors.forename: Zhao-wei
authors.initials: ZW
authors.lastname: Zeng
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Xue-qian
authors.initials: XQ
authors.lastname: Wang
authors.forename: Hui-qiang
authors.initials: HQ
authors.lastname: Li
authors.forename: Xiang-dong
authors.initials: XD
authors.lastname: Li
mesh_terms: D000328:Adult; D000818:Animals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000302:isolation & purification* / Q000378:metabolism; D011817:Rabbits; D055815:Young Adult
chemical_list: D011266:Pregnancy-Associated Plasma Protein-A