Abstract: A 28,000-dalton protein with FSH-releasing activity is isolated from porcine follicular fluid in a multi-step procedure including gel filtration, ion exchange chromatography and several reverse-phase high-performance liquid chromatography steps. The 28 kD protein promotes secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system, exhibiting an EC.sub.50 of 0.5 ng/ml. These peptides are dimers of inhibin .beta.-chains of mammals, and homodimers or heterodimers of the .beta..sub.A and .beta..sub.B chains are biologically active to regulate fertility of various mammalian species, including humans.

Abstract: Two 32,000-dalton proteins with inhibin activity were isolated from porcine follicular fluid using heparin-Sepharose affinity chromatography, followed by gel filtration on Sephacryl S-200 and then four steps of reverse-phase high-performance liquid chromatography. Each isolated molecular is composed of two chains having molecular weights of about 18,000 and about 14,000 daltons, respectively, which are bound together by disulfide bonding. Microsequencing revealed the NH.sub.2 -terminal portion of the 18K chain of both to be Ser-Thr-Ala-Pro-Leu-Pro-Trp-Pro-Trp-Ser-Pro-Ala-Ala-Leu-Arg-Leu-Leu-Gln-Ar g-Pro-Pro-Glu-Glu-Pro-Ala-Val, of one of the 14K chains to be Gly-Leu-Glu-Cys-Asp-Gly-Arg-Thr-Asn-Leu-Cys-Cys-Arg-Gln-Gln-Phe-Phe-Ile-As p-Phe-Arg-Leu-Ile-Gly-Trp, and of the other 14K chain to be Gly-Leu-Glu-Cys-Asp-Gly-Lys-Val-Asn-Ile-Cys-Cys-Lys-Lys-Gln-Phe-Phe-Val-Se r-Phe-Lys-Asp-Ile-Gly-Trp-Asn-Asp-Trp-Ile-Ile-Ala-Pro.

Abstract: A substantially purified substance has been isolated from bovine gonadal secretions which mediates pituitary hormone secretion, using an extraction and purification sequence that includes gel filtration, partition chromatography and HPLC in that order. The substance, designated gonadostatin, is a moderate-size peptide which below a threshold level selectively inhibits LRF-stimulated pituitary secretion of LH and FSH. Above a threshold level, gonadostatin generally stimulates pituitary hormone secretion.