title: Antibacterial peptides of bovine lactoferrin: purification and characterization.
abstract: Three peptides with antibacterial activity toward enterotoxigenic Escherichia coli have been purified from a pepsin digest of bovine lactoferrin. All peptides were cationic and originated from the N-terminus of the molecule in a region where a bactericidal peptide, lactoferricin B, had been previously identified. The most potent peptide, peptide I, was almost identical to lactoferricin B; the sequence corresponded to residues 17 to 42, and the molecular mass was 3195 as determined by mass spectrometry. A second, less active peptide, peptide II, consisted of two sequences, residues 1 to 16 and 43 to 48 (molecular mass of 2673), linked by a single disulfide bond. The third peptide, peptide III, also a disulfide-linked heterodimer, corresponded to residues 1 to 48 (molecular mass of 5851), cleaved between residues 42 and 43. Peptides I and II displayed antibacterial activity toward a number of pathogenic and food spoilage microorganisms, and peptide I inhibited the growth of Listeria monocytogenes at concentrations as low as 2 microM. Bacterial growth curves showed that bactericidal effects of peptides I and II were observable within 30 min of exposure. The results confirmed and extended those of earlier studies suggesting that the bactericidal domain of lactoferrin was localized in the N-terminus and did not involve iron-binding sites.
authors.affiliation: Centre for Food Technology, Department of Primary Industries, Queensland, Hamilton, Australia.
authors.forename: D A
authors.initials: DA
authors.lastname: Dionysius
authors.forename: J M
authors.initials: JM
authors.lastname: Milne
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000662:veterinary; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods / Q000662:veterinary; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D007781:Lactoferrin / Q000737:chemistry* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development; D013058:Mass Spectrometry / Q000379:methods / Q000662:veterinary; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis* / Q000302:isolation & purification* / Q000494:pharmacology; D013997:Time Factors
chemical_list: D010455:Peptides; D007781:Lactoferrin