title: On the identity of bovine seminal plasma inhibin.
abstract: In light of current discussions on multiple forms of inhibin, it was thought of interest to ascertain the identity of the postulated 'iso-hormones' of bull seminal plasma inhibin (Chari et al., 1978). By subjecting the biologically active fraction, obtained by Sephadex G-100 gel filtration of bull seminal plasma acetone powder, to extensive dialysis in distilled water adjusted to pH 5.8, it was possible to remove the bulk of inert protein as a precipitate. The resulting active preparation could be readily fractionated by preparative iso-electric focusing in the pH range 4.0-6.5 yielding 2 distinct homogeneous peptides, alpha and beta, capable of suppressing hCG-induced uterine weight increase in immature mice, in a 'reversed Steelman-Pohley' assay design. However, of these, alpha alone was able to suppress post-castrational serum gonadotropin rise in appropriate animal models. This peptide is highly acidic in nature (iso-electric point congruent to 2.2) and has a molecular weight (Mr) of 18200 and a Stokes radius of 1.90 nm. On the basis of currently available evidence, it is concluded that the molecule consists of a single peptide chain.
mesh_terms: D000818:Animals; D001681:Biological Assay; D002369:Castration; D002417:Cattle; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007265:Inhibins / Q000302:isolation & purification* / Q000494:pharmacology; D007526:Isoelectric Point; D008297:Male; D051379:Mice; D008970:Molecular Weight; D051381:Rats; D012661:Semen / Q000032:analysis*; D014599:Uterus / Q000187:drug effects
chemical_list: D007265:Inhibins; D005640:Follicle Stimulating Hormone