title: Partial purification of mare early pregnancy factor.
abstract: OBJECTIVE
  Early pregnancy factor (EPF) is an immunosuppressive protein detected in the serum in early pregnancy. We have already reported the development of the rosette inhibition test for mare EPF and have detected EPF in thoroughbreds and ponies. Here, we attempted to purify equine EPF from pregnant mare serum.
  
  
  METHODS
  Mare EPF was purified by ultrafiltration and ion-exchange chromatography. Purified EPF was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting and a neutralization test. EPF activity was estimated as the rosette inhibition titer (RIT) by the rosette inhibition test.
  
  
  RESULTS
  Purified EPF bound to carboxymethyl (CM) sepharose and did not adsorb to diethylaminoethyl (DEAE) sepharose. SDS-PAGE revealed that in the final purified fraction there were many proteins. In the immunoblotting analysis, a protein band of 25.8 kDa was detected as the pregnancy-specific band. Further, antibody gained from the 20 to 30 kDa protein band of the final purified fraction neutralized the RIT activity of pregnant mare serum.
  
  
  CONCLUSIONS
  Mare EPF was detected in the final purified fraction and had a molecular weight of 25.8 kDa. EPF in the mare is similar to that obtained from the serum of pregnant cows.
authors.affiliation: Department of Bioscience and Technology, Faculty of Agriculture, Iwate University, Ueda, Morioka-shi, Iwate, Japan. ohnuma@nias.affrc.go.jp
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ohnuma
authors.forename: Kazuei
authors.initials: K
authors.lastname: Ito
authors.forename: Jutaro
authors.initials: J
authors.lastname: Takahashi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nambo
authors.forename: Yoh-Ichi
authors.initials: Y
authors.lastname: Miyake
mesh_terms: D000818:Animals; D018835:Chaperonin 10; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006736:Horses; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000737:chemistry / Q000302:isolation & purification*; D011258:Pregnancy Tests; D011817:Rabbits; D012397:Rosette Formation; D013491:Suppressor Factors, Immunologic / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D018835:Chaperonin 10; D010455:Peptides; D011257:Pregnancy Proteins; D013491:Suppressor Factors, Immunologic; C025124:early pregnancy factor