title: Leptoglycin: a new Glycine/Leucine-rich antimicrobial peptide isolated from the skin secretion of the South American frog Leptodactylus pentadactylus (Leptodactylidae).
abstract: Antimicrobial peptides are components of innate immunity that is the first-line defense against invading pathogens for a wide range of organisms. Here, we describe the isolation, biological characterization and amino acid sequencing of a novel neutral Glycine/Leucine-rich antimicrobial peptide from skin secretion of Leptodactylus pentadactylus named leptoglycin. The amino acid sequence of the peptide purified by RP-HPLC (C(18) column) was deduced by mass spectrometric de novo sequencing and confirmed by Edman degradation: GLLGGLLGPLLGGGGGGGGGLL. Leptoglycin was able to inhibit the growth of Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Citrobacter freundii with minimal inhibitory concentrations (MICs) of 8 microM, 50 microM, and 75 microM respectively, but it did not show antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis), yeasts (Candida albicans and Candida tropicalis) and dermatophytes fungi (Microsporum canis and Trichophyton rubrum). No hemolytic activity was observed at the 2-200 microM range concentration. The amino acid sequence of leptoglycin with high level of glycine (59.1%) and leucine (36.4%) containing an unusual central proline suggests the existence of a new class of Gly/Leu-rich antimicrobial peptides. Taken together, these results suggest that this natural antimicrobial peptide could be a tool to develop new antibiotics.
authors.affiliation: Laboratório de Toxinologia e Farmacologia Molecular, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, CE 60.740-000, Brazil.
authors.forename: Juliana C
authors.initials: JC
authors.lastname: Sousa
authors.forename: Raquel F
authors.initials: RF
authors.lastname: Berto
authors.forename: Elicélia A
authors.initials: EA
authors.lastname: Gois
authors.forename: Nauíla C
authors.initials: NC
authors.lastname: Fontenele-Cardi
authors.forename: José E R
authors.initials: JE
authors.lastname: Honório
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Konno
authors.forename: Michael
authors.initials: M
authors.lastname: Richardson
authors.forename: Marcos F G
authors.initials: MF
authors.lastname: Rocha
authors.forename: Antônio A C M
authors.initials: AA
authors.lastname: Camargo
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Pimenta
authors.forename: Bruno A
authors.initials: BA
authors.lastname: Cardi
authors.forename: Krishnamurti M
authors.initials: KM
authors.lastname: Carvalho
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D005260:Female; D005658:Fungi / Q000187:drug effects; D005998:Glycine / Q000737:chemistry; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007202:Indicators and Reagents; D007930:Leucine / Q000737:chemistry; D008297:Male; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011898:Ranidae / Q000378:metabolism*; D012867:Skin / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D007202:Indicators and Reagents; C543474:leptoglycin, Leptodactylus pentadactylus; D007930:Leucine; D005998:Glycine