Amphibian peptides : their structures and bioactivity / by Kate Louise Wegener.

Abstract

The skin secretion of the northern Australian frog Litoria dahlii was investigated, with eleven novel peptides identified. These peptides have moderate biological activity, including antibacterial and anticancer actions, as well as the capacity to inhibit the enzyme neuronal nitric oxide synthase. Many potent broad-spectrum antibiotics have been isolated from Australian amphibians, and are believed to act by disrupting the bacterial cell membrane by forming transmembrane 'barrel-stave' type ion channels, lipid-incorporating toroidal pores or by assembling as a 'carpet' over the mebrane surface. The structures of several antibacterial peptides were determined using nuclear magnetic resonance spectroscopy and restrained molecular dynamics calculations. Experimental results suggest these peptides operate by the 'carpet' mechanism.