title: Structural study of novel antimicrobial peptides, nigrocins, isolated from Rana nigromaculata.
abstract: Novel cationic antimicrobial peptides, named nigrocin 1 and 2, were isolated from the skin of Rana nigromaculata and their amino acid sequences were determined. These peptides manifested a broad spectrum of antimicrobial activity against various microorganisms with different specificity. By primary structural analysis, it was revealed that nigrocin 1 has high sequence homology with brevinin 2 but nigrocin 2 has low sequence homology with any other known antimicrobial peptides. To investigate the structure-activity relationship of nigrocin 2, which has a unique primary structure, circular dichroism (CD) and homonuclear nuclear magnetic resonance spectroscopy (NMR) studies were performed. CD investigation revealed that nigrocin 2 adopts mainly an alpha-helical structure in trifluoroethanol (TFE)/H(2)O solution, sodium dodecyl sulfate (SDS) micelles, and dodecylphosphocholine micelles. The solution structures of nigrocin 2 in TFE/H(2)O (1:1, v/v) solution and in SDS micelles were determined by homonuclear NMR. Nigrocin 2 consists of a typical amphipathic alpha-helix spanning residues 3-18 in both 50% TFE solution and SDS micelles. From the structural comparison of nigrocin 2 with other known antimicrobial peptides, nigrocin 2 could be classified into the family of antimicrobial peptides containing a single linear amphipathic alpha-helix that potentially disrupts membrane integrity, which would result in cell death.
authors.affiliation: Research Institute of Pharmaceutical Science, College of Pharmacy, Seoul National University, Seoul, South Korea.
authors.forename: S
authors.initials: S
authors.lastname: Park
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: H C
authors.initials: HC
authors.lastname: Ahn
authors.forename: S
authors.initials: S
authors.lastname: Kim
authors.forename: S S
authors.initials: SS
authors.lastname: Kim
authors.forename: B J
authors.initials: BJ
authors.lastname: Lee
authors.forename: B J
authors.initials: BJ
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins; D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects; D002942:Circular Dichroism; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D016982:Micrococcus luteus / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011898:Ranidae / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012867:Skin / Q000737:chemistry; D012996:Solutions
chemical_list: D029845:Amphibian Proteins; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008823:Micelles; D012996:Solutions; C439762:nigrocin 1 protein, Rana nigromaculata; C439763:nigrocin 2 protein, Rana nigromaculata