The long term goal of this project is to advance our general understanding of the structure-function relationships in pituitary prolactins and gonadotropins. This proposal outlines specific groups of experiments, designed to broaden our data base with respect to both conserved and non-conserved primary, secondary, tertiary and quaternary structural features, and further correlation of these features with the presence of biochemical parameters. The recent discovery and preliminary descriptions of at least 3 atypical forms of prolactin will be exploited to study the structural and functional roles of the various disulfide bonds and tryptophan residues in this class of hormones. The complementation of prolactin fragments will be further investigated in order to prepare semi-synthetic analogues. An extensive conformational study of equine-LH is of particular interest in view of this molecule's intrinsic FSH-like activity. These experiments will include the novel application of second-order spectroscopy. Of equal importance is a thorough conformational evaluation of partially deglycosylated ovine-LH, its subunits, and hybrids formed with native oLH subunits.