title: Antimicrobial peptides from diverse families isolated from the skin of the Asian frog, Rana grahami.
abstract: Seven peptides with antimicrobial activity were isolated in pure form from an extract of the skin of the Yunnanfu Kunming frog Rana grahami Boulenger, 1917. The peptides were identified as belonging to the nigrocin-2 (three peptides), brevinin-1 (one peptide), brevinin-2 (three peptides), and esculentin-1 (one peptide) families. Nigrocin-2GRb (GLFGKILGVGKKVLCGLSGMC) containing three lysine residues, represented the peptide with highest potency against microorganisms (MIC = 3 microM against Escherichia coli, 12.5 microM against Staphylococcus aureus and 50 microM against Candida albicans) and the greatest hemolytic activity against human erythrocytes (LD50 = 40 microM). In contrast, nigrocin-2GRa (GLLSGILGAGKHIVCGLSGLC) and nigrocin-2GRc (GLLSGILGAGKNIVCGLSGLC), with only a single lysine residue, showed weak antimicrobial and hemolytic activity. Phylogenetic relationships among Eurasian ranid frogs are less well understood than those of North American ranids but the primary structures of the R. grahami antimicrobial peptides suggest a close relationship of this species with the Japanese pond frogs R. nigromaculata and R. porosa brevipoda.
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, 17666 Al-Ain, United Arab Emirates. jmconlon@uaeu.ac.ae
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
authors.forename: Nadia
authors.initials: N
authors.lastname: Al-Ghaferi
authors.forename: Bency
authors.initials: B
authors.lastname: Abraham
authors.forename: Hu
authors.initials: H
authors.lastname: Jiansheng
authors.forename: Pascal
authors.initials: P
authors.lastname: Cosette
authors.forename: Jérôme
authors.initials: J
authors.lastname: Leprince
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D011898:Ranidae / Q000145:classification / Q000378:metabolism*; D012867:Skin / Q000737:chemistry*
chemical_list: D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; C092874:esculentin protein, Rana esculenta; C078413:brevinin-1 protein, Rana; C078414:brevinin-2, Rana