Phenylalanine/tyrosine ammonia-lyase

{{Infobox enzyme

| Name = Phenylalanine/tyrosine ammonia-lyase

| EC_number = 4.3.1.25

| CAS_number =

| GO_code =

| image =

| width =

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Phenylalanine/tyrosine ammonia-lyase (EC 4.3.1.25, PTAL, bifunctional PAL) is an enzyme with systematic name L-phenylalanine(or L-tyrosine):trans-cinnamate(or trans-p-hydroxycinnamate) ammonia-lyase.{{cite journal | vauthors = Rösler J, Krekel F, Amrhein N, Schmid J | title = Maize phenylalanine ammonia-lyase has tyrosine ammonia-lyase activity | journal = Plant Physiology | volume = 113 | issue = 1 | pages = 175–9 | date = January 1997 | pmid = 9008393 | pmc = 158128 | doi = 10.1104/pp.113.1.175 }}{{cite journal | vauthors = Watts KT, Mijts BN, Lee PC, Manning AJ, Schmidt-Dannert C | title = Discovery of a substrate selectivity switch in tyrosine ammonia-lyase, a member of the aromatic amino acid lyase family | journal = Chemistry & Biology | volume = 13 | issue = 12 | pages = 1317–26 | date = December 2006 | pmid = 17185227 | doi = 10.1016/j.chembiol.2006.10.008 | doi-access = }}{{cite journal | vauthors = Louie GV, Bowman ME, Moffitt MC, Baiga TJ, Moore BS, Noel JP | title = Structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases | journal = Chemistry & Biology | volume = 13 | issue = 12 | pages = 1327–38 | date = December 2006 | pmid = 17185228 | pmc = 2859959 | doi = 10.1016/j.chembiol.2006.11.011 }}{{cite journal | vauthors = Schwede TF, Rétey J, Schulz GE | title = Crystal structure of histidine ammonia-lyase revealing a novel polypeptide modification as the catalytic electrophile | journal = Biochemistry | volume = 38 | issue = 17 | pages = 5355–61 | date = April 1999 | pmid = 10220322 | doi = 10.1021/bi982929q }}{{cite journal | vauthors = Barros J, Serrani-Yarce JC, Chen F, Baxter D, Venables BJ, Dixon RA | title = Role of bifunctional ammonia-lyase in grass cell wall biosynthesis | journal = Nature Plants | volume = 2 | issue = 6 | pages = 16050 | date = May 2016 | pmid = 27255834 | doi = 10.1038/nplants.2016.50 }} This enzyme catalyses the following chemical reaction

: (1) L-phenylalanine $\backslash rightleftharpoons$ trans-cinnamate + NH₃

: (2) L- tyrosine $\backslash rightleftharpoons$ trans-p-hydroxycinnamate + NH₃

This enzyme is a member of the aromatic amino acid lyase family.