1) Amino acid 2) Chelating agent 
Domoic acid is a toxic amino acid produced by certain species of algae. Domoic acid binds to a receptor that helps nerve cells control the flow of ions across their cell membranes. The receptor no longer works correctly, and the uncontrolled flux of ions damages and eventually kills the nerve cell.
Domoic acid (DA), the neurotoxin that causes amnesic shellfish poisoning (ASP), is a kainic acid analog, heterocyclic amino acid associated with certain harmful algal blooms. ==Occurrence== In 1958, domoic acid was originally isolated from the red alga called `doumoi` or `hanayanagi` (Chondria armata) in Japan. `Doumoi` is used as an anthelm...
(from the article `algae`) Not all shellfish poisons are produced by dinoflagellates. Amnesic shellfish poisoning is caused by domoic acid, which is produced by diatoms (class ...
<biochemistry> An excitatory amino acid transmitter. ... (15 Nov 1997) ... 
An excitatory amino acid transmitter.
noun a neurotoxin that is deadly for humans; found in various marine algae