NEW ANTIBIOTIC UPERIN PEPTIDES FROM THE DORSAL GLANDS OF THE AUSTRALIAN TOADLET UPEROLEIA-MJOBERGII

The dorsal glandular extract of the toadlet Uperoleia mjobergii contai ns more than 20 peptides. We report the amino acid sequences of the se ven major peptides: these were determined by a combination of mass spe ctrometry and automated Edman sequencing. Three of these peptides have 19 amino acid residues and belong to the uperin 2 group of peptides [ e.g. uperin 2.6, euAspIleAlaLysLysLeuValGlyGlyIleArgAsnValLeuGlyIle (O H)], while the other four have 17 residues and are classified as uperi ns 3 [e.g. uperin 3.4, lyValGlyAspLeuIleArgLysAlaValAlaAlaIleLysAsnIle Val (NH2)]. Several of these cationic peptides have been synthesized i n order for bioassays to be carried out: they show significant antibio tic activity against a range of Gram-positive microorganisms. A major skin peptide from the related species Uperoleia inundata is a powerful neuropeptide named uperin 1.1 ([Ala(2)]uperolein): no corresponding n europeptide is detected in the skin glands of Uperoleia mjobergii.