The ultimate objectives are (1) to place our understanding of the mode of action of the peptide antibiotics and hormones on a conformational basis and (2) to develop the spectroscopic approach to the study of conformation and conformational averaging in peptides. The experimental approach involves the combined use of (a) solid phase peptide synthesis (b) correlation, double resonance, and difference NMR spectroscopy (c) fluorescence and circular dichroism (d) thin film and equilibrium dialysis and (e) model building. In addition, we intend to investigate the interaction of the peptide antibiotics and hormones with a view to understanding (a) the sites for detergent and fluorescent probe binding (b) the rates and mechanism of cleavage by crystallographically defined proteases and (c) the structure and thermodynamics of peptide micelle formation. The availability of conformationally characterized peptides lends those studies uniqueness; they also have considerable importance for control and regulation of hormone levels--hormone homeostasis.