IUBMB Enzyme Nomenclature


Accepted name: phenylalanine/tyrosine ammonia-lyase

Reaction: (1) L-phenylalanine = trans-cinnamate + NH3
(2) L-tyrosine = trans-p-hydroxycinnamate + NH3

Other name(s): PTAL; bifunctional PAL

Systematic name: L-phenylalanine(or L-tyrosine):trans-cinnamate(or trans-p-hydroxycinnamate) ammonia-lyase

Comments: This enzyme is a member of the aromatic amino acid lyase family, other members of which are EC (histidine ammonia-lyase), EC (tyrosine ammonia-lyase) and EC (phenylalanine ammonia-lyase). The enzyme from some monocots, including maize, and from the yeast Rhodosporidium toruloides, deaminate L-phenylalanine and L-tyrosine with similar catalytic efficiency [3]. The enzyme contains the cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO), which is common to this family [3]. This unique cofactor is formed autocatalytically by cyclization and dehydration of the three amino-acid residues alanine, serine and glycine [4].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Rösler, J., Krekel, F., Amrhein, N. and Schmid, J. Maize phenylalanine ammonia-lyase has tyrosine ammonia-lyase activity. Plant Physiol. 113 (1997) 175-179. [PMID: 9008393]

2. Watts, K.T., Mijts, B.N., Lee, P.C., Manning, A.J. and Schmidt-Dannert, C. Discovery of a substrate selectivity switch in tyrosine ammonia-lyase, a member of the aromatic amino acid lyase family. Chem. Biol. 13 (2006) 1317-1326. [PMID: 17185227]

3. Louie, G.V., Bowman, M.E., Moffitt, M.C., Baiga, T.J., Moore, B.S. and Noel, J.P. Structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases. Chem. Biol. 13 (2006) 1327-1338. [PMID: 17185228]

4. Schwede, T.F., Rétey, J. and Schulz, G.E. Crystal structure of histidine ammonia-lyase revealing a novel polypeptide modification as the catalytic electrophile. Biochemistry 38 (1999) 5355-5361. [PMID: 10220322]

[EC created 2008 (EC created 1965, part-incorporated 2008)]

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