Characterization of a Novel P-Superfamily Peptide from Conus regiusVenom. 

M.C.V. Braga¹; D.C. Pimenta²; K. Konno²; J.C. Freitas¹; F.C.V. Portaro²; T. Yamane³ and A.C.  Cassola⁴.

1 IB/USP, São Paulo, SP, Brazil; 2 CAT/CEPID, Butantan Institute, São Paulo, SP, Brazil, 3 Butantan Institute, São Paulo, SP, Brazil; 4 ICB/USP, São Paulo, SP, Brazil.

Cone snails are very slow predators from tropical seas. They have evolved a very complex venom that paralyzes their prey quickly and efficiently. Conus toxin is a mixture of peptides that act specifically on ionic channels and/or neuromuscular receptors of the prey. Some of the peptides are noteworthy pharmacological tools. Conus regius is a vermivorous member of this genus that inhabits Northeastern Brazilian tropical waters. Some peptides present in its venom are being characterized. The present work will introduce a new peptide named rg9a. Crude venom was purified by reverse phase HPLC and selected fractions were screened and sequenced by mass spectrometry, MALDI-TOF and ESI-Q-TOF, respectively. The sequence revealed a 26 amino acid peptide (2,862 Da) with three disulfide cross-links. The pattern of cysteines (C-C-C-C-C-C) suggests that this peptide belongs to a new group of the conotoxins, the “P superfamily”. The biological activity of the purified peptide was tested by intracranial injection in mice and the observed biological effect was dose dependent. Higher doses of rg9a induced hyperactivity in animals, whereas lower doses caused respiratory depression. Current work is still in progress in order to further characterize the action of this conotoxin in ionic channels.

Acknowledgments: IBAMA, Águas Claras Dive Center, CEBIMar/USP and Dr. Baldomero Olivera (University of Utah). 

Financial support: FAPESP.

Correspondence to: mcbraga@usp.br