Beta-Hairpin This is bovine pancreatic trypsin inhibitor, a small protein with a long, and twisted beta-hairpin in yellow. The beta-hairpin is flanked by two short alpha-helices Parkin, S.,  Rupp, B.,  Hope, H. Structure of bovine pancreatic trypsin inhibitor at 125 K: Acta Crystallogr D Biol Crystallogr v52 pp.18-29, 199 (Link) 1bpi (PDB)