Abstract
A novel conotoxin (conopeptide) was biochemically characterized from the crude venom of the molluscivorous marine snail, Conus bandanus (Hwass in Bruguière, 1792), collected in the south-central coast of Vietnam. The peptide was identified by screening bromotryptophan from chromatographic fractions of the crude venom. Tandem mass spectrometry techniques were used to detect and localize different post-translational modifications (PTMs) present in the BnIIID conopeptide. The sequence was confirmed by Edman’s degradation and mass spectrometry revealing that the purified BnIIID conopeptide had 15 amino acid residues, with six cysteines at positions 1, 2, 7, 11, 13, and 14, and three PTMs: bromotryptophan, γ-carboxy glutamate, and amidated aspartic acid, at positions “4”, “5”, and “15”, respectively. The BnIIID peptide was synthesized for comparison with the native peptide. Homology comparison with conopeptides having the III-cysteine framework (–CCx1x2x3x4Cx1x2x3Cx1CC–) revealed that BnIIID belongs to the M-1 family of conotoxins. This is the first report of a member of the M-superfamily containing bromotryptophan as PTM.
Highlights
The peptides from the venom of cone snails constitute a rich source of useful pharmacological tools and peptide probes for ion channels, transporters, and neurotransmitter receptors with a high degree of diversity, specificity, and potency [1,2,3]
In the search of new conopeptides from the venom of Conus bandanus, collected from the coast of Vietnam, we have found an unusual peptide containing bromine
We suggest that the BnIIID conopeptide could share the same disulfide connectivity as the MrIIIE peptide
Summary
The peptides from the venom of cone snails (conotoxins or conopeptides) constitute a rich source of useful pharmacological tools and peptide probes for ion channels, transporters, and neurotransmitter receptors with a high degree of diversity, specificity, and potency [1,2,3]. Most mature peptides range between 8 and 40 amino acid residues with various cysteine-framework, and inter-cyteine variations in the number and kind of amino acids. They have a high degree of post-translational modifications (PTMs) [7], whereby the modifications serve to create efficiently new conotoxin structures and pharmacological properties [4]. We used tandem mass spectrometry to characterize the primary peptide sequence and localize the positions of tryptophan bromination, and γ-carboxylation of glutamic acid. The BnIIID peptide was synthesized for comparison with the native peptide This is the first report of an M-superfamily conopeptide containing a bromotryptophan
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