A novel family of potentially bioactive cyclic peptides named PawS-Derived Peptides (PDP) found in the sunflower family has been described recently. The genetic structure of its first member, a 14-amino acid long cyclic peptide with trypsin inhibitory activity called sunflower trypsin inhibitor 1 (SFTI-1), revealed an unusual biosynthesis. The sequence of SFTI-1 is buried within a linear precursor protein that also gives rise to a seed storage albumin. The head-to-tail cyclization of SFTI-1 and maturation of the seed storage albumin PawS1 are mediated by asparaginyl endopeptidases (AEP). Seed storage albumins provide a source of sulphur and nitrogen for the developing seedling and represent the most important source of animal and human nutrition, and as a result are potential targets for genetic manipulation to increase seed nutritional values. SFTI-1 and other PawS-Derived Peptides are characterized by exceptional stability and thus have potential applications in protein engineering or as peptide based templates for drug design. This study provides new structural insights into seed storage albumins, PawS-Derived Peptides and the mechanism by which these proteins are processed into their mature form. We have investigated the abundance and structural features of seed storage albumins in sunflower seeds (Helianthus annuus) in order to create a detailed map of the albumins found at a protein level and to elucidate their structural characteristics. Furthermore we use solution NMR spectroscopy to describe the structural diversity and physiochemical properties of PDPs to extend our knowledge of this new class of cyclic peptides.