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Anthranilate Synthase 1i1q 3D Rendering of Anthranilate Synthase
Identifiers
EC no.	4.1.3.27
CAS no.	9031-59-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

In enzymology, an anthranilate synthase (EC 4.1.3.27) 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 (EC 4.1.3.27) is an enzyme that catalyzes the chemical reaction

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

Chemical equation of reaction occurring in anthranilate synthase

.

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

• chorismate pyruvate-lyase (amino-accepting).

This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis and two-component system - general.

Structural studies

As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1I1Q, 1I7Q, 1I7S, 1QDL, and 2I6Y.

References

• Baker TI, Crawford IP (1966). "Anthranilate synthetase. Partial purification and some kinetic studies on the enzyme from Escherichia coli". J. Biol. Chem. 241 (23): 5577–84. PMID 5333199.
• Creighton TE and Yanofsky C (1970). "Chorismate to tryptophan (Escherichia coli) - Anthranilate synthetase, PR transferase, PRA isomerase, InGP synthetase, tryptophan synthetase". Methods Enzymol. 17A: 365–380.
• Kung CC, Huang WN, Huang YC, Yeh KC (2006). "Proteomic survey of copper-binding proteins in Arabidopsis roots by immobilized metal affinity chromatography and mass spectrometry". Proteomics. 6 (9): 2746–58. doi:10.1002/pmic.200500108. PMID 16526091.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• Ito J, Yanofsky C (1969). "Anthranilate synthetase, an enzyme specified by the tryptophan operon of Escherichia coli: Comparative studies on the complex and the subunits". J. Bacteriol. 97 (2): 734–42. PMC 249753. PMID 4886290.
• Zalkin H, Kling D (1968). "Anthranilate synthetase. Purification and properties of component I from Salmonella typhimurium". Biochemistry. 7 (10): 3566–73. doi:10.1021/bi00850a034. PMID 4878701.

Category:EC 4.1.3 Category:Enzymes of known structure Category:Anthranilates