Brinkworth, C.Carver, J.Wegener, K.Doyle, J.Llewellyn, L.Bowie, J.2007-11-052007-11-052003Biopolymers, 2003; 70(3):424-4340006-35251097-0282http://hdl.handle.net/2440/39363The definitive version may be found at www.wiley.comThe peptide frenatin 3 is a major component of the skin secretion of the Australian giant tree frog, Litoria infrafrenata. Frenatin 3 is 22 amino acids in length, and shows neither antimicrobial nor anticancer activity. It inhibits the production of nitric oxide by the enzyme neuronal nitric oxide synthase at a micromolar concentration by binding to its regulatory protein, Ca2+ calmodulin, a protein known to recognize and bind amphipathic alpha-helices. The solution structure of frenatin 3 has been investigated using NMR spectroscopy and restrained molecular dynamics calculations. In trifluoroethanol/water mixtures, the peptide forms an amphipathic alpha-helix over residues 1-14 while the C-terminal eight residues are more flexible and less structured. The flexible region may be responsible for the lack of antimicrobial activity. In water, frenatin 3 exhibits some alpha-helical character in its N-terminal region.enamphibian peptidesneuronal nitric oxide synthase inhibitionNMR spectroscopysolution structureJournal article002003099510.1002/bip.105240001864358000132-s2.0-024255126958470Wegener, K. [0000-0002-1562-6060]