Moving pieces in a proteomic puzzle: mass fingerprinting of toxic fractions from the venom of Tityus serrulatus (Scorpiones, Buthidae)

Scorpion venoms are very complex mixtures of molecules, most of which are p eptides that display different kinds of biological activity. These venoms h ave been studied in the light of their pharmacological targets and their co nstituents are able to bind specifically to a variety of ionic channels loc ated in prey tissues, resulting in neurotoxic effects. Toxins that modulate Na+, K+, Ca++ and Cl- currents have been described in scorpion venoms. Mas s spectrometry was employed to analyze toxic fractions from the venom of th e Brazilian scorpion Tityus serrulatus in order to shed light on the molecu lar composition of this venom and to facilitate the search for novel pharma cologically active compounds. T. serrulatus venom was first subjected to ge l filtration to separate its constituents according to their molecular size . The resultant fractions II and III, which account for 90 and 10% respecti vely of the whole venom toxic effect, were further analyzed by matrix-assis ted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), on-line liquid chromatography/electrospray mass spectrometry (LC/ESMS) and off-line LC/MALDI-TOFMS in order to establish their mass fingerprints. The molecular masses in fraction II were predominantly between 6500 and 75 00 Da. This corresponds to long-chain toxins that mainly act on voltage-gat ed Na+ channels. Fraction III is more complex and predominantly contained m olecules with masses between 2500 and 5000 Da. This corresponds to the shor t-chain toxin family, most of which act on K+ channels, and other unknown p eptides. Finally, we were able to measure the molecular masses of 380 diffe rent compounds present in the two fractions investigated. To our knowledge, this is the largest number of components ever detected in the venom of a s ingle animal species. Some of the toxins described previously from T. serru latus venom could be detected by virtue of their molecular masses. The inte rpretation of this large set of data has provided us with useful proteomic information on the venom, and the implications of these findings are discus sed. Copyright (C) 2001 John Wiley & Sons, Ltd.