Conus Venoms: A Rich Source of Neuroactive Peptides

Purification of toxins from the venoms of two fish-hunting gastropod cone snails, Conus geographus and Conus magus has revealed the presence of three classes of paralytic peptide toxins. These are: 1) the w-conotoxins, which block voltage activated calcium channels at the presynaptic terminus; 2) the α-conotoxins, which block the acetylcholine receptor and 3) the ω-conotoxins, which inhibit muscle sodium channels, and therefore prevent propagation of the muscle action potential. These toxins are basic peptides from 13–27 amino acids long, rich in cystine residues which are present as disulfides. A number of α-conotoxins and one a-conotoxin have been chemically synthesized.In addition to the paralytic conotoxins, the venoms of Conus have other toxins which have not yet been completely characterized. A large number of neuroactive peptides and proteins have also been found. Since there are approximately 300 species of Conus, all of which produce venoms, the cone snails promise to be a rich source of neuroactive peptides in the years ahead.