title: Antimicrobial activity of a bovine hemoglobin fragment in the tick Boophilus microplus.
abstract: Antifungal and antibacterial activities were detected in the hemolymph and gut contents of the cattle tick, Boophilus microplus. A peptide with antibacterial activity from the tick gut contents was purified to homogeneity by reversed-phase chromatography. The molecular mass of the purified peptide was 3,205.7 Da, measured by matrix-assisted laser desorption/ionization mass spectrometry. The amino acid sequence was obtained by Edman degradation and showed that the peptide was identical to a fragment of the bovine alpha-hemoglobin. A synthetic peptide based on the sequence obtained showed characterization data identical to those of the isolated material, confirming its structure. The synthetic peptide was active in micromolar concentrations against Gram-positive bacteria and fungi. These data led us to conclude that the antibacterial activity detected in tick gut contents is the result of enzymatic processing of a host protein, hemoglobin. This activity may be used by ticks as a defense against microorganisms.
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, CEP 05508-900, São Paulo, Brazil.
authors.forename: A C
authors.initials: AC
authors.lastname: Fogaça
authors.forename: P I
authors.initials: PI
authors.lastname: da Silva
authors.forename: M T
authors.initials: MT
authors.lastname: Miranda
authors.forename: A G
authors.initials: AG
authors.lastname: Bianchi
authors.forename: A
authors.initials: A
authors.lastname: Miranda
authors.forename: P E
authors.initials: PE
authors.lastname: Ribolla
authors.forename: S
authors.initials: S
authors.lastname: Daffre
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D002417:Cattle; D005658:Fungi / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006454:Hemoglobins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D013987:Ticks / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D006454:Hemoglobins; D010446:Peptide Fragments