Profiling the peptidome of the venom from the social wasp Agelaia pallipes pallipes Nicoli Barão Baptista-Saidemberg, Daniel Menezes Saidemberg, Mario Sergio Palma ⁎ CEIS/Department of Biology, Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, SP-13506-900 - Brazil National Institute of Science and Technology (INCT) in Immunology (iii), CNPq/MCT- Brazil ARTICLE INFO ABSTRACT Article history: Received 6 April 2011 Accepted 5 June 2011 Available online 14 June 2011 The wasp Agelaia pallipes pallipes is one of the most aggressive species from the neotropical region, causing many stinging accidents every year, characterized by severe envenoming reactions. The identification of peptides is important for understanding the envenoming process; however, the tiny amount of venom produced by these insects makes this task a challenge, using classical analytical approaches. Thus, the venom was previously fractionated, and the sequences were obtained through the use of electrospray ionization with a tridimensional ion-trap and time-of-flight mass analysis under CID conditions. This approach permitted the sequence assignment of nine peptides. The presence of type -d and -w ions generated from the fragmentation of the side chains was used to resolve I/L ambiguity. The distinction between K and Q residues was achieved through esterification of the α- and ε-amino groups in the peptides, followed by mass spectrometry analysis. Six of these peptides were short, linear and polycationic, while the three other peptides presented a single disulfide bridge. The use of reduction and alkylation protocols, followed by ESI-IT- TOF/MS analysis under CID conditions, permitted easy sequencing of the three peptides presenting this post-translational modification. These peptides presented activity related to mast cell degranulation, hemolysis, or even the chemotaxis of leukocytes. © 2011 Elsevier B.V. All rights reserved. Keywords: Peptidomics RP-HPLC ESI-IT-TOF/MS Polycationic peptides Wasp venom 1. Introduction The venoms of wasps, bees and ants are generally used both for self-defense and to repel predators and/or intruders of the nest [1]. The stings caused by these insects produce severe pain, local edema and erythema caused by an increase in the permeability of the blood vessels close to the skin, local tissue damage and occasionally death in large vertebrates, including man [2]. Deleterious effects on kidney, liver, muscles, and even red blood cells have been attributed to wasp venom toxins; thus, hepatic and renal lesion, hemolysis, and vasoactive properties caused by wasp venom toxins may cause intravas- cular haemolysis, haemoglobinuria, and rhabdomyolysis [3] which result in multi-organ failure, followed by death [4]. The wasp venoms are composed of low molecular mass compounds, proteins and peptides [5]; peptides constitute approximately 70% of the venom components [6]. These peptides may have pharmacological actions such as mast cell degranulation, chemotaxis of polymorphonuclear leuko- cytes (PMNL), cytolysis and smooth muscle contraction [7,8]. The identification of the peptides in venoms is important to characterize the pharmacological symptoms observed during the envenoming process. This knowledge will help physicians to assist the victims of stinging incidents. The pharmacolog- ical properties of wasp venoms have not yet been fully investigated because of the limited production of venom by the wasps and due to the low abundance of each natural peptide in these venoms. JOURNAL OF PROTEOMICS 74 (2011) 2123 – 2137 ⁎ Corresponding author. CEIS/Department of Biology, Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, SP-13506-900 - Brazil. Tel./fax: + 55 19 35264365. E-mail address: mspalma@rc.unesp.br (M.S. Palma). 1874-3919/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jprot.2011.06.004 available at www.sciencedirect.com www.elsevier.com/locate/jprot