Biologically Active Hormones Prepared by Recombination of the α Chain of Human Chorionic Gonadotropin and the Hormone-Specific Chain of Bovine Thyrotropin or of Bovine Luteinizing Hormone

A mixture of equal weights of the β (hormone-specific) chain of bovine thyrotropin and the α chain of human chorionic gonadotropin yields thyroid-stimulating activity similar to that observed by recombination of the two chains of thyrotropin itself. Recombination to yield gonadotropic activity occurs between the α chain of the chorionic gonadotropin and the hormone-specific chain of luteinizing hormone from bovine pituitaries. The data provide strong evidence that an α type chain, whose structure has been shown to be nearly identical in bovine pituitary thyrotropin and luteinizing hormones, is also utilized in the placenta for the formation of its gonadotropic hormone.