Fortunately, the identification of molecules using mass spectrometry analysis is helping to characterize these neglected molecules and change the current scenario [14] and [15]. Through natural selection, scorpion venoms molecules were conserved to act upon certain physiological mechanisms which are shared by a great variety of organisms, including

human beings. Therefore, it is probable that compounds like scorpion venom peptides can be prototypes for the development of new drugs. For example, the chlorotoxin (CTX) from the scorpion Leiurus quinquestriatus was first described as a chloride toxin [8], but nowadays it has been shown to be effective against the human glioma brain tumor via inhibition of the MMP-2, an important metallopeptidase over-expressed by tumor cells [22]. This fact Epacadostat price suggests that novelties are still to be discovered, including new functions for already known molecules. Thimet oligopeptidase (EP24.15) belongs to the M3 family metallopeptidase BGB324 [13] and was first described as a neuropeptide-degrading enzyme present in the soluble fraction of brain homogenates [12]. The EP24.15 does not have a clear primary

specificity to cleave substrates, with the ability to accommodate different amino acid residues at subsites S4 to S3′ [11]. In fact, EP24.15 shows substrate size restriction to peptides containing from 5 to 17 amino acids because of its catalytic center, located in a deep channel [17]. These features of EP24.15 were decisive in successfully describing two new peptides: the human hemopressin [19] and a potent inhibitor of ACE in the venom of Bothrops

jararacussu [20]. Considering the property of EP24.15 to select small molecules and its presence in the nervous system, where the TsV mainly acts, the objective of this study was to find in TsV new bioactive peptides selected by interaction with EP24.15 activity in vitro. The lyophilized TsV, provided by Butantan Institute, São Paulo, Brazil, was suspended in sodium acetate pH 4.0 and immediately fractionated at 4 °C using a 10 kDa molecular weight cut off membrane (Millipore), Methocarbamol in order to prevent proteolytic cleavage of peptides by the crude venom. The filtrated solution (Peptide Pool) was subjected to reverse phase HPLC (Prominence, Shimadzu), using a Shim-pack VP-ODS C-18 column (4.6 × 150 mm); 0.1% TFA in water (solvent A), and acetonitrile plus solvent A (9:1) as solvent B. The chromatography was performed at a flow rate of 1 mL/min and detected by ultraviolet absorption (214 nm). The peaks were collected manually, dried and subjected to enzymatic assays. The recombinant EP24.15 was obtained as described [18]. The peptidase assay was conducted in a 50 mM phosphate and 20 mM NaCl 7.