RANATUERINS - ANTIMICROBIAL PEPTIDES ISOLATED FROM THE SKIN OF THE AMERICAN BULLFROG, RANA-CATESBEIANA

Nine peptides, termed ranatuerins 1-9, with antimicrobial activity tow ards Staphylococcus aureus, were isolated from an extract of the skin of the adult American bullfrog, Rana catesbeiana. In common with other cytolytic peptides from Ranid frogs, (e.g. ranalexin, gaegurins, brev inins), ranatuerins 1 and 4 contain an intramolecular disulfide bridge forming a heptapeptide ring whereas in ranatuerins 2 and 3 the disulf ide bridge forms a hexapeptide ring. The structurally related ranatuer ins 5-9 comprise 12 - 14 amino acids and show sequence similarity towa rds the hemolytic peptides Al and B9 previously isolated from the skin of Rana esculenta. Of the peptides purified, ranatuerin 1 (SMLSVLKNLG KVGLG FVACKINKQC) showed the broadest spectrum of antimicrobial action with inhibitory activity against S. aureus, Escherichia coli and Cand ida albicans. (C) 1998 Academic Press.