title: Processing of an antibacterial peptide from hemocyanin of the freshwater crayfish Pacifastacus leniusculus.
abstract: An antibacterial peptide with 16 amino acid residues was found in plasma of the freshwater crayfish, Pacifastacus leniusculus. This peptide, designated astacidin 1, was purified by cation-exchange column chromatography and reverse-phase high performance liquid chromatography. Astacidin 1 has a broad range of antibacterial activity, and it inhibits growth of both Gram-positive and Gram-negative bacteria. The primary sequence of astacidin 1 was FKVQNQHGQVVKIFHH-COOH. The molecular mass was 1945.2 Da, and no carbohydrate-linked amino acid residues could be found by mass spectrometry. A synthetic astacidin 1 resulted in similar activity as the authentic astacidin 1 against Gram-positive bacteria, whereas it had less or no activity against Gram-negative bacteria. Three amino-terminal-truncated synthetic peptides were made; they all showed low activity, suggesting that the amino-terminal part of astacidin 1 contributes to the antibacterial activity. The structure of astacidin 1 based on the CD results showed that it has a beta-sheet structure in citric acid buffer at pH 4, 6, and 8. Cloning of astacidin 1 shows that it is the carboxyl-terminal part of crayfish hemocyanin and that astacidin 1 is produced by a proteolytic cleavage from hemocyanin under acidic conditions. The processing and release of astacidin 1 from hemocyanin is enhanced when crayfish are injected with lipopolysaccharide or glucan.
authors.affiliation: Department of Comparative Physiology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18A, SE-752 36, Sweden.
authors.forename: So Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Bok Luel
authors.initials: BL
authors.lastname: Lee
authors.forename: Kenneth
authors.initials: K
authors.lastname: Söderhäll
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D003400:Astacoidea; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D005618:Fresh Water; D005936:Glucans / Q000008:administration & dosage; D006433:Hemocyanins / Q000737:chemistry*; D006458:Hemolymph / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008969:Molecular Sequence Data; D010455:Peptides; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000900:Anti-Bacterial Agents; D005936:Glucans; D008070:Lipopolysaccharides; D010455:Peptides; D004247:DNA; D006433:Hemocyanins