Novel uperin peptides from the dorsal glands of the Australian floodplain toadlet Uperoleia inundata

The dorsal glandular extract of the floodplain toadlet Uperoleia inundata contains more than 50 peptides: we report the amino acid sequences and bioactivity data of 13 of these. The peptides have been sequenced by using a combination of mass spectrometry and automated Edman sequencing. Ten of the peptides have been synthesized in order to confirm their structures, and to enable bioassays to be carried out. Ten peptides are host-defence agents, including (i) a powerful new neuropeptide of the tachykinin family which we name uperin 1.1 [pGluAlaAspProAsnAlaPheTyrGlyLeuMet(NH2)], and (ii) nine antibiotic peptides including five uperins 2 [e.g. uperin 2.1, GlyIleValAspPheAlaLysLysValValGlyGlyIleArgAsnAlaLeuGlyIle(OH)], three uperins 3 [e.g. uperin 3.1, GlyValLeuAspAlaPheArgLysIleAlaThrValValLysAsnValVal(NH2)] and uperin 4.1 [GlyValGlySerPheIleHisLysValValSerAlaIleLysAsnValAla(NH2)]. The function of the three other characterized peptides in the amphibian integument is not known, viz. (i) uperin 5.1 [PheGlnPheValAsnProSerAspIleValPheGlySer(OH)] and (ii) the two uperins 6 [e.g. uperin 6.1, GlyLeuAlaGlyAlaIleSerSerAlaLeuAspLys LeuLysGlnSerGlnLeuIleLysAsnTyrAlaLysLysLeuGlyTyrProArg(OH)].