Poster 146 - A new peptide isolated from the neurotoxic fraction of Bunodosoma caissarum venom

Poster 146. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.505.

A New Peptide Isolated From the Neurotoxic Fraction of Bunodosoma caissarum Venom Has a BcIII-like Action on the Crab Nerve.

^1,2Oliveira, J.S; ¹Ferreira Jr., W.A.;^1,2Zaharenko, A.J.; ²Konno, K. and ^1,2Freitas, J.C.

1 Departamento de Fisiologia do Instituto de Biociências, USP, São Paulo, Brazil; 2 Center for Applied Toxinology, CAT/CEPID- FAPESP, Instituto Butantan, São Paulo, Brazil.

B. caissarum is an endemic Brazilian sea anemone that possesses a venom containing a wide range of bioactive compounds. Hemolytic proteins and neurotoxic peptides are the main molecules responsible to promote paralysis of preys. Many neurotoxins from sea anemones were useful in dissecting the functional role and biophysical properties of ion channels from distinct tissues. We have reported previously from a neurotoxic fraction of B. caissarum gel-filtered venom a major neurotoxin, BcIII, which prolongs the inactivation phase of a family of voltage gated sodium channels. BcIII belongs to type-I sea anemone toxins and its effect is similar to AFTII and ATXII, isolated from the sea anemones Anthopleura fuscoviridis and Anemonia sulcata, respectivelly (Oliveira et al., 2004. Nav 1.1-1.6 Sodium Channels Binding Specificity to Sea Anemone Toxins: Unexpected Contributions from Changes in the IV/ S3-S4 Outer Loop., J BIOL CHEM, in press). Here we present a new peptide from the B. caissarum venom exhibiting a BcIII-like action on the crab leg nerve bioassay. This novel peptide was purified from the same neurotoxic gel-filtered fraction as that yielded BcIII by RP-HPLC with a C-18 column. The molecule is more hydrophobic than BcIII and its molecular weight was determined by mass spectrometry (MALDI-TOF and ESI-Q-TOF) to be 4,669. By comparing this molecular mass to those reported from other anemone species, we consider this toxin completely novel. Employing the “sucrose-gap” technique, this molecule apparently is a low affinity peptide, since at least 10mM are required to affect the crab compound action potentials. BcIII and AFTII are highly and rapidly active at only 1mM in this assay. The toxin is also slower than BcIII and AFTII in its onset. At present primary sequence analysis and patch-clamp recording are in progress.