Bovine fetus-specific serum proteins. Purification and characterization of alpha1-fetoprotein and immunological identification of alpha2- and beta-fetoproteins.

Bovine alpha1-fetoprotein was isolated from fetal calf serum by successive procedures of concanavalin A-Sepharose chromatography, DEAE-Sephadex chromatography, SP-Sephadex chromatography and preparative disc polyacrylamide gel electrophoresis. The bovine alpha1-fetoprotein preparation was considered homogeneous by several physicochemical and immunochemical criteria. Bovine alpha1-fetoprotein has a molecular weight of 68 000 with an amino acid composiotn similar to that of other mammalian alhpa1-fetoprotein. In addition, bovine alpha1-fetoprotein was shown to exist as two distinct variants on the basis of carbohydrate heterogeneity. alpha2-Fetoprotein and a new beta-fetoprotein were immunologically identified in fetal calf serum. These fetoproteins, like alpha1-fetoprotein, were not detectable in non-pregnant cow serum by immunoelectrophoresis.