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Abstract

From six Conus species (Conus coronatus, Conus lividus, Conus mozambicus f. lautus, Conus pictus, Conus sazanka, Con us tinianus) collected off the eastern coast of South Africa the venoms were analyzed using MALDI-TOF mass spectrometry. Between 56 and 151 molecular masses most in a range of 1000 to 2500 Da, were identified. Among the six venoms, between 0 and 27% (C coronatus versus C. sazanka) of the peptide masses were found to be similar. In a study on venoms from 6 Conus species collected in the Philippines, the percentage of identical masses was between none and 9% only. The venoms from the South African Conus species antagonized the rat neuronal nicotinic acetylcholine receptors (nAChRs) alpha 3 beta 2, alpha 4 beta 2, and alpha 7, except for C coronatus venom that blocked the alpha 4 beta 2 and alpha 7 nAChRs only. HPLC-fractionation of C tinianus venom led to the isolation of a peptide that is active on all three receptor subtypes. It consists of 16 amino acid residues crosslinked by two disulfide bridges as revealed by de novo sequencing using tandem mass spectrometry: GGCCSHPACQNNPDYC. Posttranslational modifications include C-terminal amidation and tyrosine sulfation. The new peptide is a member of the alpha-conotoxin family that are competitive antagonists of nAChRs. Phylogenetic analysis of the 16S RNA from numerous Conus species has clarified the evolutionary position of endemic South African Conus species and provided the first evidence for their close genetic relationships. (C) 2010 Elsevier Ltd. All rights reserved.