Domoic acid is an L-proline derivative that is L-proline substituted by a carboxymethyl group at position 3 and a 6-carboxyhepta-2,4-dien-2-yl group at position 4. It is produced by the diatomic algal Pseudo-nitzschia. It is an analogue of kainic acid and a neurotoxin which causes amnesic shellfish poisoning (ASP). It has a role as a neurotoxin, a marine metabolite, a hapten, a neuromuscular agent and an algal metabolite. It is a pyrrolidinecarboxylic acid, a tricarboxylic acid, a L-proline derivative and a non-proteinogenic L-alpha-amino acid. It is a conjugate acid of a domoate(2-).