Take One Snail And Call Me In The Morning...continued
Small and Specific
A need for speedy action also explains the size of the conotoxins. As with many toxins, such as those from spiders and scorpions, the conotoxins are strings of amino acids called peptides. But the conotoxin peptides have between ten and thirty amino acids, whereas many other toxins have over one hundred amino acids each. Their small size means that conotoxins diffuse rapidly into the fish.
And this diffusion is not slowed by attachment of the conotoxins to irrelevant protein molecules, because the conotoxins attach themselves very specifically to one protein in the nervous system.
For the pharmaceutical industry this story was starting to sound more and more attractive. Small molecules are easy to make, and specific molecules should work as potent drugs with few side-effects.
The first company to push a conotoxin through drug trials is Neurex Corporation (Menlo Park, Calif.). Their drug, called SNX-111 or ziconotide, is an omega-conotoxin that blocks the entry of calcium ions into nerve cells. This prevents the nerve cells from releasing packets of nerve messengers to communicate with their neighbors.
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