Antimicrobial peptides of the brevinin-2 family isolated from gastric tissue of the frog, Rana esculenta

Four structurally related peptides with potent growth-inhibitory activity t owards Escherichia coli were isolated from an extract of the stomach of the European green frog Rana esculenta, and were identified as members of the brevinin-2 family. Two peptides, termed brevinin-2Eg (GIMDTLKNLA(10) KTAGK- GALQS(20) LLNHASCK LS(30)GQC) and brevinin-2Eh (GIMDTLKNLA(10) KTAGKGALQS(2 0) LLNHASCKL S-30 KQC) have not been described previously. One peptide is i dentical to brevinin-2Ec, previously isolated from R. esculenta skin secret ions, and one peptide is identical to brevinin-2Ef whose structure has been deduced from a cloned cDNA prepared from a R. esculenta skin cDNA library. The data demonstrate that certain peptides of the brevinin-2 family, like the magainins in the toad, Xenopus laevis, may play an important role in pr otecting the gastrointestinal tract of Ranid frogs against microbial invasi on. (C) 1998 Academic Press.