Chemical Properties
Off-White Solid
Uses
An amino acid that is able to function as an agonist at multiple excitatory amino acid receptor substrates in the central nervous system. It also has high affinity for the kainate, AMPA and the metabotropic receptors. Inhibits the Ca2+/Cl-dependent glutamic acid uptake system in brain synaptic plasma membrane preparations.
Biological Activity
Glutamate receptor agonist acting at AMPA receptors and metabotropic glutamate receptors positively linked to phosphoinositide hydrolysis. Sensitizes neurons in hippocampus to depolarization by L-AP6 (the so called 'quis' effect). Also available as part of the Group I mGlu Receptor Tocriset™ .
Description
L-Quisqualic acid is a natural analog of glutamate that acts as an agonist at AMPA-selective and metabotropic glutamate receptors (EC50s = 170, 10, 40, and 29 nM at GluR-A, mGluR1, mGluR3, and mGluR5, respectively), as well as the ionotropic kainate receptor (GRIK4; Ki = 6.43 nM). L-Quisqualic acid is used to study receptor dynamics and as an excitotoxin to selectively destroy neurons in the brain or spinal cord.
Definition
ChEBI: Quisqualic acid is a non-proteinogenic alpha-amino acid.
General Description
Quisqualate/ Quisqualic acid is obtained from the fruits and seeds of Quisqualis chinensis. It is an agonist at two subsets of excitatory amino acid receptors metabotropic receptors that indirectly mediate calcium mobilization from intracellular stores and, ionotropic receptors that directly control membrane channels. L-quisqualic acid is an agonist of the neurotransmitter L-glutamate.
Biochem/physiol Actions
Active enantiomer of quisqualic acid; excitatory amino acid at glutamate receptors.
Purification Methods
It has been purified by ion-exchange chromatography on Dowex 50W (x 8, H+ form); the desired fractions are lyophilised and recrystallised from H2O/EtOH. It has IR (KBr) : 3400-2750br, 1830s, 1775s, 1745s and 1605s cm-1;maxand 1H NMR (NaOD/D2O, pH 13) : 3.55-3.57 (1H m, X of ABX, H-2), 3.72-3.85 (2H, AB of ABX, H-3), 1 3C NMR (D2O) : 50.1t, 53.4d, 154.8s, 159.7s and 171.3s. [Baldwin et al. J Chem Soc, Chem Commun 256 1985.] It is a quasiqualate receptor agonist [Joels et al. Proc Natl Acad Sci USA 86 3404 1989].
