Isolation, purification and functional characterization of alpha-BnIA from Conus bandanus venom

We report the isolation and characterization by proteomic approach of a native conopeptide, named BnIA, from the crude venom of Conus bandanus, a molluscivorous cone snail species, collected in the South central coast of Vietnam. Its primary sequence was determined by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry using collision-induced dissociation and confirmed by Edman's degradation of the pure native fraction. BnIA was present in high amounts in the crude venom and the complete sequence of the 16 amino acid peptide was the following GCCSHPACSVNNPDIC*, with C-terminal amidation deduced from Edman's degradation and theoretical monoisotopic mass calculation. Sequence alignment revealed that its -C(1)C(2)X4C(3)X7C(4)-pattern belongs to the A-superfamily of conopeptides. The cysteine connectivity of BnIA was 1-3/2- 4 as determined by partial-reduction technique, like other alpha 4/7-conotoxins, reported previously on other Conus species. Additionally, we found that native alpha-BnIA shared the same sequence alignment as Mr1.1, from the closely related molluscivorous Conus marmoreus venom, in specimens collected in the same coastal region of Vietnam. Functional studies revealed that native alpha-BnIA inhibited acetylcholine-evoked currents reversibly in oocytes expressing the human alpha 7 nicotinic acetylcholine receptors, and blocked nerveevoked skeletal muscle contractions in isolated mouse neuromuscular preparations, but with similar to 200-times less potency. (C) 2014 Elsevier Ltd. All rights reserved.