Homoquinolinic acid (HQA) is a potent
excitotoxin
In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate re ...
which is a conformationally-restricted
analogue of
''N''-methyl-D-aspartate (NMDA) and a
partial agonist
In pharmacology, partial agonists are drugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist. They may also be considered ligands which display both agonistic and antagonistic e ...
of the main/
glutamate
Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can syn ...
site of the
NMDA receptor
The ''N''-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA rece ...
, with some selectivity for
NR2B subunit-containing receptors.
It is approximately
equipotent
In mathematics, two sets or classes ''A'' and ''B'' are equinumerous if there exists a one-to-one correspondence (or bijection) between them, that is, if there exists a function from ''A'' to ''B'' such that for every element ''y'' of ''B'', the ...
to NMDA and about five times more potent than
quinolinic acid as an agonist of the NMDA receptor.
HQA has also been found to label a novel, yet uncharacterized
binding site, which can be distinguished from the NMDA receptor with the use of
2-carboxy-3-carboxymethylquinoline (CCMQ), a selective
ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...
of the uncharacterized site.
See also
*
Aspartate
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
*
Ibotenic acid
Ibotenic acid or (''S'')-2-amino-2-(3-hydroxyisoxazol-5-yl)acetic acid, also referred to as ibotenate, is a chemical compound and psychoactive drug which occurs naturally in ''Amanita muscaria'' and related species of mushrooms typically found i ...
*
Tetrazolylglycine
Tetrazolylglycine (Tet-Gly, LY-285,265) is a potent and selective NMDA receptor agonist, stimulating the NMDA receptor with higher potency than either glutamate or NMDA. It is a potent convulsant and excitotoxin
In excitotoxicity, nerve cells ...
References
Dicarboxylic acids
Convulsants
Neurotoxins
NMDA receptor agonists
Pyridines
Excitotoxins
Aromatic acids
{{nervous-system-drug-stub