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In enzymology, an anthranilate synthase is an enzyme that catalyzes the chemical reaction


 * chorismate + L-glutamine $$\rightleftharpoons$$ anthranilate + pyruvate + L-glutamate 2

Thus, the two substrates of this enzyme are chorismate and L-glutamine, whereas its 3 products are anthranilate, pyruvate, and L-glutamate.

Function
Chorismate is a precursor in plants for at least four metabolic pathways. These four pathways lead to the formation of Trp, Phe/Tyr, salicylate/phylloquinone, and folate. The four enzymes that compete for are CM, anthranilate synthase (AS), isochorismate synthase (ICS), and aminodeoxychorismate synthase (ADCS) each catalyzing for their respective pathway.

The AS enzyme is allosterically inhibited by tryptophan, which binds to AS∝ preventing conformational change. This suggests that AS∝ is responsible for feedback inhibition by tryptophan.]

Reaction
Anthranilate synthase is an enzyme that catalyzes the chemical reaction
 * chorismate + L-glutamine $$\rightleftharpoons$$ anthranilate + pyruvate + L-glutamate

. Thus, the two substrates of this enzyme are chorismate and L-glutamine, whereas its 3 products are anthranilate, pyruvate, and L-glutamate.

[AS∝ binds to chorismate and catalyzes the amination and pyruvate elimination reaction whereas ASβ hydrolyzes glutamine and provides ammonia to AS∝. The binding of chorismate to AS∝ triggers a conformational change to an active state and creates an intermolecular channel for ammonia transfer from ASβ to AS∝.]

Homologues
This enzyme is found in a number of eukaryotic species including saccharomyces cerevisiae, kluyveromyces lactis, schizosaccharomyces pombe, magnaporthe oryzae, neurospora crassa, arabidopsis thaliana, and oryza sativa.

Structure
Anthranilate synthase is made up of a large alpha and small beta subunits capable of forming alpha/beta heterodimers or an a2/b2 tetramer.

Nomenclature
This enzyme belongs to the family of lyases, to be specifica the oxo-acid-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is chorismate pyruvate-lyase (amino-accepting; anthranilate-forming). Other names in common use include
 * anthranilate synthetase
 * chorismate lyase

This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis and two-component system - general.
 * chorismate pyruvate-lyase (amino-accepting).

Structural studies
As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes, , , , and.