Table of Contents
International Journal of Peptides
Volume 2013, Article ID 543028, 9 pages
http://dx.doi.org/10.1155/2013/543028
Research Article

α-RgIB: A Novel Antagonist Peptide of Neuronal Acetylcholine Receptor Isolated from Conus regius Venom

1CAT/CEPID, Instituto Butantan, Avenida Vital Brasil 1500, 05503-900 São Paulo, SP, Brazil
2Ministério da Ciência, Tecnologia e Inovação, Esplanada dos Ministérios, Bloco E, 70067-900 Brasília, DF , Brazil
3Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-900 São Paulo, SP, Brazil
4Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
5Laboratório de Bioquímica e Biofísica, Instituto Butantan, Avenida Vital Brasil 1500, 05503-900 São Paulo, SP, Brazil

Received 31 October 2012; Revised 16 January 2013; Accepted 16 January 2013

Academic Editor: Ayman El-Faham

Copyright © 2013 Maria Cristina Vianna Braga et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Conus venoms are rich sources of biologically active peptides that act specifically on ionic channels and metabotropic receptors present at the neuromuscular junction, efficiently paralyzing the prey. Each species of Conus may have 50 to 200 uncharacterized bioactive peptides with pharmacological interest. Conus regius is a vermivorous species that inhabits Northeastern Brazilian tropical waters. In this work, we characterized one peptide with activity on neuronal acetylcholine receptor (nAChR). 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. A new peptide was identified, bearing two disulfide bridges. The novel 2,701 Da peptide belongs to the cysteine framework I, corresponding to the cysteine pattern CC-C-C. The biological activity of the purified peptide was tested by intracranial injection in mice, and it was observed that high concentrations induced hyperactivity in the animals, whereas lower doses caused breathing difficulty. The activity of this peptide was assayed in patch-clamp experiments, on nAChR-rich cells, in whole-cell configuration. The peptide blocked slow rise-time neuronal receptors, probably α3β4 and/or α3β4α5 subtype. According to the nomenclature, the new peptide was designated as α-RgIB.