Biological and immunological activities of bovine placental gonadotropin

A bovine placental extract was fractionated on a Concanavalin A (ConA)-Sepharose column into an unadsorbed ConA I fraction and an adsorbed ConA II fraction. The ConA II fraction was then separated by gel filtration on Sephadex G-100 into void volume material (ConA II Sephadex fraction I) and retarded material (ConA II Sephadex fraction II). Con A II Sephadex fraction II was considerably more potent than ConA II Sephadex fraction I in stimulating testosterone production by isolated rat Leydig cells. Con A I fraction was inactive in this regard. None of the aforementioned fractions manifested follicle stimulating hormone (FSH) bioactivity. ConA II Sephadex fraction II yielded a displacement curve parallel to the standard curve in radioimmunoassays for rat luteinizing hormone and thyroid stimulating hormone (TSH), but it did not cross-react in a radioimmunoassay for rat FSH. ConA II fraction did not exhibit FSH bioactivity. The results indicate that bovine placental gonadotropin possesses luteinizing hormone-like bioactivity and immunoreactivity and TSH immunoreactivity but neither FSH bioactivity nor immunoreactivity.