1. Antimicrobial peptides of the brevinin-2 family isolated from gastric tissue of the frog, Rana esculenta
Y Wang, F C Knoop, I Remy-Jouet, C Delarue, H Vaudry, J M Conlon Biochem Biophys Res Commun. 1998 Dec 30;253(3):600-3. doi: 10.1006/bbrc.1998.9822.
Four structurally related peptides with potent growth-inhibitory activity towards 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 (GIMDTLKNLA10 KTAGKGALQS20 LLNHASCK LS30GQC) and brevinin-2Eh (GIMDTLKNLA10 KTAGKGALQS20 LLNHASCKL S30 KQC) have not been described previously. One peptide is identical to brevinin-2Ec, previously isolated from R. esculenta skin secretions, 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 protecting the gastrointestinal tract of Ranid frogs against microbial invasion.
2. Solution structure of antimicrobial peptide esculentin-1c from skin secretion of Rana esculenta
Su-Jin Kang, Woo-Sung Son, Kyung-Doo Han, Tsogbadrakh Mishig-Ochir, Dae-Woo Kim, Jae-Il Kim, Bong-Jin Lee Mol Cells. 2010 Nov;30(5):435-41. doi: 10.1007/s10059-010-0135-7. Epub 2010 Sep 10.
Granular glands in the skins of frogs synthesize and secrete a remarkably diverse range of peptides capable of antimicrobial activity. These anuran skin antimicrobial peptides are commonly hydrophobic, cationic and form an amphipathic α-helix in a membrane mimetic solution. Recently, they have been considered as useful target molecules for developing new antibiotics drugs. Esculentin-1c is a 46-amino acid residue peptide isolated from skin secretions of the European frog, Rana esculenta. It displays the most potent antimicrobial activity among bioactive molecules. Esculentin-1c has the longest amino acids among all antimicrobial peptides. The present study solved the solution structure of esculentin-1c in TFE/water by NMR, for the first time. We conclude that this peptide is comprised of three α-helices with each helix showing amphipathic characteristics, which seems to be a key part for permeating into bacterial membranes, thus presenting antimicrobial activity.
3. An atypical member of the brevinin-1 family of antimicrobial peptides isolated from the skin of the European frog Rana dalmatina
J Michael Conlon, Bernhard Seidel, Per F Nielsen Comp Biochem Physiol C Toxicol Pharmacol. 2004 Feb;137(2):191-6. doi: 10.1016/j.cca.2004.01.003.
A single peptide with antimicrobial activity was extracted from the skin of the European agile frog (R. dalmatina). The primary structure of this 17 amino-acid-residue peptide (ILPLLLGKVVCAITKKC) does not immediately suggest membership of any of the previously described families of antimicrobial peptides from ranid frogs. However, if it is assumed that the peptide has undergone several residue deletions during the course of speciation, it shows sequence similarity with peptides belonging to the widely distributed brevinin-1 family, particularly those isolated from the related species Rana temporaria. The minimum inhibitory concentration of the peptide, termed brevinin-1 Da, against the Gram-positive bacterium Staphylococcus aureus was 7 microM and against the Gram-negative bacterium Escherichia coli was 30 microM.
