The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis. Part 2. Sequence determination using electrospray mass spectrometry

Abstract

Sixteen aurein peptides are present in the host defence secretion from the granular dorsal glands of the Green and Golden Bell Frog Litoria aureus and seventeen from those of the related Southern Bell Frog Litoria raniformis. All peptides have been sequenced using a combination of electrospray mass spectrometry and Lys-C digestion, with each sequence confirmed by automated Edman sequencing. The peptides are named in five groups, viz. aureins 1-5. Ten of these peptides are common to both species of frog. Thirteen of the aurein peptides show wide-spectrum antibiotic and anticancer activity. Amongst the more active peptides are aurein 1.2 (GLFDIIKKIAESF-NH2), the smallest peptide from an anuran reported to have both antibiotic and anticancer activity; aurein 2.2 (GLLDIVKKVIGAFGSL-NH2) and aurein 3.1 (GLFDIVKKIAGHIAGSI-NH2). The aurein 4 and 5 peptides, e.g. aurein 4.1 (GLIQTIKEKLKELAGGLVTGIQS-OH) and aurein 5.1 (GLLDIVTGLLGNLIVDVLKPKTPAS-OH), show neither antibacterial nor anticancer activity.