PURIFICATION, MOLECULAR MASS AND N-TERMINAL DETERMINATION OF AN INSECTICIDAL TOXIN FROM THE VENOM OF THE Grammostola iheringi (MYGALOMORPHAE: THERAPHOSINAE)

MONTANDON G. G. (1,2,3), SANTOS D. M. (2,3), FERRAZ, K. K. F. (2,3), BEMQUERER, M. P. (3), PIMENTA, A. M. C. (2,3), MONTENEGRO, F. C. (4), LUCAS, S. M. (5), CORDEIRO, M. N. (6), De LIMA M.E. (2,3), DINIZ M.R.V. (7).

(1) Bolsista Programa de Educação Tutorial (PET– MEC/SESu) Ciências Biológicas da Pontifícia Universidade Católica de Minas Gerais (PUC Minas); (2) Laboratório de Venenos e Toxinas Animais (LVTA); (3) Núcleo de Biomoléculas; (4) Laboratório de Membranas Excitáveis, Depto. Bioquímica e Imunologia, ICB, UFMG; (5) Laboratório de Artrópodes, Instituto Butantan; (6) Laboratório de Bioquímica e Química de Proteínas, Fundação Ezequiel Dias (FUNED); (7) Laboratório de Biologia Molecular II, Fundação Ezequiel Dias (FUNED).

Venomous animals have evolved a vast array of peptide toxins for prey capture and defense. These peptides are directed against a wide variety of pharmacological targets, making them an invaluable source of ligands for studying the properties of these targets in different experimental paradigms. In this respect, spiders as a highly diversified group of almost exclusive insect predators appear to possess great potential for the discovery of novel insect-selective toxins. Only the venom of a tiny percentage of the 40.000 known spiders have been well characterized. In this work, we fractionated the crude venom of Grammostola iheringi by RP-HPLC which yielded 40 fractions that were collected manually and assayed for paralytic activity for house fly (Musca domestica). Seventeen fractions were toxic to insects, being two of them further purified and characterized. The biochemical characterization involved the N-terminal sequence - SXQQKWMWTXGQQX - established by direct automated Edman degradation, and the molecular mass of 3587 Da determined by mass spectrometry. BLAST searches revealed similarity with spider potassium channel inhibitory toxin family and this result was confirmed by tests in channels Kv1.3 from L929 cells.

KEY WORDS: spider, spider venom, Grammostola iheringi, insecticidal toxin.

FINANCIAL SUPPORT: Fapemig, CNPq

CORRESPONDENCE TO: Dr. Marcelo Ribeiro Vasconcelos Diniz. E-mail:  mdiniz@funed.mg.gov.br