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Catalytic Site Atlas

CSA LITERATURE entry for 1ax4

E.C. nametryptophanase
SpeciesProteus vulgaris ()
E.C. Number (IntEnz)
CSA Homologues of 1ax4There are 19 Homologs
CSA Entries With UniProtID P28796
CSA Entries With EC Number
PDBe Entry 1ax4
PDBSum Entry 1ax4
MACiE Entry 1ax4

Literature Report

IntroductionTryptophan indole-lyase (also known as tryptophanase or Trpase) is a pyridoxal 5'-phosphate (PLP) dependent enzyme that catalyses the reversible beta-elimination reaction of L-Tryptophan to form indole and ammonium pyruvate. The enzyme has been found in a wide variety of Gram-negative bacteria.
MechansimThe catalytic cycle of tryptophanase consists of the following steps: (1) Association of the amino acid substrate with the enzyme to form the Michaelis complex; (2) Formation of the external aldimine (transaldimination); (3) Quinonoid formation by alpha-proton abstraction from the external aldimine; (4) Tautomerisation of the indolyl group; (5) Elimination of indole and formation of the aminoacrylate Schiff base intermediate; (6) Restoration of the internal aldimine (transaldimination); (7) Release of aminoacrylate and decomposition to pyruvate and ammonia.

Catalytic Sites for 1ax4

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
TyrA7272macie:sideChainGeneral acid, directly transfers a proton to the indole side group to assist with tautomerisation.
AspA133133macie:sideChainGeneral base to remove the proton from the NH group of indole.
HisA458458macie:sideChainForms a hydrogen bond with the carboxylate anion of Asp133 to stabilise the negative charge in hydrophobic conditions.

Literature References

Kulikova VV
Tryptophanase from Proteus vulgaris: the conformational rearrangement in the active site, induced by the mutation of Tyrosine 72 to phenylalanine, and its mechanistic consequences.
Biochim Biophys Acta 2006 1764 750-757
PubMed: 16455316
Isupov MN
Crystal structure of tryptophanase.
J Mol Biol 1998 276 603-623
PubMed: 9551100
Demidkina TV
Spatial structure and mechanism of tyrosine phenol-lyase and tryptophan indole-lyase
Mol Biol (Mosk) 2009 43 295-308
PubMed: 19425498