[57] Disassembly and assembly of glycoprotein hormones

One group of polypeptide hormones, the glycoprotein hormones of the anterior pituitary and the placenta and related tissues, exhibits features otherwise not found in the large number of polypeptides now recognized to have hormonal activities. These hormones, luteinizing hormone (LH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and chorionic gonadotropin consist of two distinct peptide chains, both rich in intra chain disulfides and both glycosylated. One chain or subunit (α) has, within a species, essentially the same amino acid sequence from hormone to hormone; the other subunits (β), while probably evolving from a single primitive gene, have different sequences. These sequences, when correctly folded, must contain the information, which upon combination with α subunit, gives rise to a specific hormone activity. The interaction between the two subunits is solely via non-covalent forces, and the formation of a hormonally active α–β dimer is accompanied by changes in conformation of both subunits. In the future, high-performance liquid chromatography shows the most promise for rapid and easy separation of subunits and some initial results.