IntEnz

EC 4.1.99.1 - Tryptophanase

IntEnz Enzyme Nomenclature
EC 4.1.99.1

Names

Reactions

• (1) L-tryptophan + H2O = indole + pyruvate + NH3
•   (1a) L-tryptophan = indole + 2-aminoprop-2-enoate
•   (1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous)
•   (1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)

Cofactors

• K⁺
• pyridoxal 5'-phosphate

Comments:

A pyridoxal-phosphate protein, requiring K+. The enzyme cleaves a carbon-carbon bond, releasing indole and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form pyruvate and ammonia. The latter reaction, which can occur spontaneously, can also be catalysed by EC 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase. Also catalyses 2,3-elimination and β-replacement reactions of some indole-substituted tryptophan analogues of L-cysteine, L-serine and other 3-substituted amino acids.

Links to other databases

References

1. Burns, R.O. and DeMoss, R.D.
   Properties of tryptophanase from Escherichia coli.
   Biochim. Biophys. Acta 65 : 233-244 (1962). [PMID: 14017164]
2. Cowell, J.L., Maser, K. and DeMoss, R.D.
   Tryptophanase from Aeromonas liquifaciens. Purification, molecular weight and some chemical, catalytic and immunological properties.
   Biochim. Biophys. Acta 315 : 449-463 (1973).
3. Newton, W.A., Morino, Y. and Snell, E.E.
   Properties of crystalline tryptophanase.
   J. Biol. Chem. 240 : 1211-1218 (1965). [PMID: 14284727]
4. Snell, E. E.
   Tryptophanase: structure, catalytic activities, and mechanism of action.
   Adv. Enzymol. Relat. Areas Mol. Biol. 42 : 287-333 (1975). [PMID: 236639]

[EC 4.1.99.1 created 1972]