title: Structural and functional characterization of N-terminally blocked peptides isolated from the venom of the social wasp Polybia paulista.
abstract: Two novel peptides were isolated from the crude venom of the social wasp Polybia paulista, by using RP-HPLC under a gradient of MeCN from 5 to 60% (v/v) and named Polybine-I and -II. Further purification of these peptides under normal phase chromatography, rendered pure enough preparations to be sequenced by Edman degradation chemistry. However, both peptides did not interact with phenylisothiocyanate reagent, suggesting the existence of a chemically blocked N-terminus. Therefore, the sequences of both peptides were assigned by ESI-MS/MS under CID conditions, as follows: Polybine-I Ac-SADLVKKIWDNPAL-NH2 (Mr 1610 Da) and Polybine-II Ac-SVDMVMKGLKIWPL-NH2 (Mr 1657 Da). During the tandem mass spectrometry experiments, a loss of 43 a.m.u. was observed from the N-terminal residue of each peptide, suggesting the acetylation of the N-terminus. Subsequently, the peptides with and without acetylation were synthesized on solid phase and submitted to functional characterizations; the biological activities investigated were: hemolysis, chemotaxis of polymorphonucleated leukocytes (PMNL), mast cell degranulation and antibiosis. The results revealed that the acetylated peptides exhibited more pronounced chemotaxis of PMNL cells and mast cell degranulation than the respective non-acetylated congeners; no hemolytic and antibiotic activities were observed, irrespective to the blockage or not of the alpha-amino groups of the N-terminal residues of each peptide. Therefore, the N-terminal acetylation may be related to the increase of the inflammatory activity of both peptides.
authors.affiliation: Department of Biology, CEIS/IBRC, UNESP, Rio Claro, SP, CEP 13506-900, Brazil.
authors.forename: Susan Pereira
authors.initials: SP
authors.lastname: Ribeiro
authors.forename: Maria Anita
authors.initials: MA
authors.lastname: Mendes
authors.forename: Lucilene Delazari
authors.initials: LD
authors.lastname: Dos Santos
authors.forename: Bibiana Monson
authors.initials: BM
authors.lastname: de Souza
authors.forename: Maurício Ribeiro
authors.initials: MR
authors.lastname: Marques
authors.forename: Walter Filgueira
authors.initials: WF
authors.lastname: de Azevedo
authors.forename: Mario Sergio
authors.initials: MS
authors.lastname: Palma
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D015550:Cell Degranulation / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D006460:Hemolysin Proteins / Q000302:isolation & purification / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D051381:Rats; D021241:Spectrometry, Mass, Electrospray Ionization; D014862:Wasp Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D014863:Wasps
chemical_list: D000900:Anti-Bacterial Agents; D006460:Hemolysin Proteins; D010455:Peptides; D014862:Wasp Venoms; C500842:polybine-I protein, Polybia paulista; C500843:polybine-II protein, Polybia paulista