title: Isolation and structures of grammistins, peptide toxins from the skin secretion of the soapfish Grammistes sexlineatus.
abstract: Two peptide toxins (named grammistins Gs 1 and Gs 2) with hemolytic and ichthyotoxic activities were isolated from the skin secretion of the soapfish Grammistes sexlineatus. Grammistin Gs 2 showed 6-11 x higher hemolytic activity and 10x higher ichthyotoxicity than grammistin Gs 1. The complete amino acid sequences of Gs 1 comprising 25 residues and Gs 2 comprising 24 residues were determined. Although a search by the database failed to find any homologous toxins from other sources, the grammistins were similar in secondary structures as well as biological activities to the two classes of peptide toxins, melittin from the bee venom and pardaxins from the skin secretion of two species of soles. CD experiments and helical wheel projections showed that the grammistins were randomly coiled in distilled water but formed amphiphilic alpha-helices in the presence of SDS micelles. In addition, they were found to be surface seeking peptides by the Eisenberg plot and assumed to exist as aggregates of 3-4 molecules. Interestingly, grammistin Gs 2 is much more abundant in amphiphilic alpha-helices and much higher in biological activities than melittin and pardaxins as well as grammistin Cs 1.
authors.affiliation: Department of Food Science and Technology, Tokyo University of Fisheries, Japan. shiomi@tokyo-u-fish.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Shiomi
authors.forename: T
authors.initials: T
authors.lastname: Igarashi
authors.forename: H
authors.initials: H
authors.lastname: Yokota
authors.forename: Y
authors.initials: Y
authors.lastname: Nagashima
authors.forename: M
authors.initials: M
authors.lastname: Ishida
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005397:Fish Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D005400:Fishes, Poisonous / Q000378:metabolism*; D006461:Hemolysis / Q000187:drug effects; D006736:Horses; D066298:In Vitro Techniques; D007928:Lethal Dose 50; D008387:Marine Toxins / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D008969:Molecular Sequence Data; D009990:Oryzias; D011817:Rabbits; D012756:Sheep; D012867:Skin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005397:Fish Venoms; D008387:Marine Toxins; C001882:grammistin