STRUCTURAL AND FUNCTIONAL CHARACTERIZATION OF N-TERMINAL BLOCKED PEPTIDES ISOLATED FROM THE VENOM OF THE SOCIAL WASP POLYBIA PAULISTA

Ribeiro, S. P.¹; Mendes, M. A.¹; Souza, B.M.¹;Marques, R.M.¹; Santos, L.D.¹; Azevedo Jr, W. F.²; Palma, M.S.¹

1 Dept. Biology -CEIS / IBRC - UNESP - Rio Claro, SP, CEP: 13506-900 – Brazil; 2 Dept. Physics, IBILCE-UNESP, S.J.Rio Preto, SP- Brazil

The venoms of Hymenoptera have been known to cause significant effects such as systemic reactions and allergy. Currently little is known about the structure, chemical composition and mechanisms of action of the toxins present in the venoms of wasps from the Neotropical regions, responsible for high number of harmful stinging incidents every year.

Two new peptides were isolated from the crude venom of social wasp Polybiapaulista, by using RP-HPLC under a gradient of MeCN from 5 to 60% (v/v). The new peptides have eluted in the high hydrophobicity region and presented molecular masses of 1611 Da and 1658 Da (determined by ESI-MS). After the purification, these peptides have shown pure enough to be sequenced by Edman Degradation Chemistry. However, both peptides have not interacted to phenylisothiocyanate reagent by suggesting the existence of a chemically blocked N-terminus. Thus, the sequences of both peptides were assigned by ESI-MS/MS, as follows: Ac-SADLVKIWDNPAL-NH2 (Mr 1611 Da) and Ac-SVDMVMKGLKIWPL (Mr 1658 Da). During the tandem mass spectrometry experiments a loss of 42 u.m.a. was observed from the N-terminal residue of each peptide by 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 have revealed that the acetylated peptides have exhibited more pronounced chemotaxis of PMNL and mast cell degranulation than the non-acetylated ones. Thus, the N-terminal acetylation may be related to the potentiation of the inflammatory activity of both peptides.

Financial Support: FAPESP (SMOLBNET and CAT-CEPID); Institute of Immunological Investigations (Millennium Institute-MCT/CNPq).