Phenylalanine ammonia-lyase (IPR005922)

Short name: Phe_NH3-lyase

Overlapping homologous superfamilies

Family relationships


The ubiquitous higher plant enzyme phenylalanine ammonia-lyase (PAL; EC: is a key biosynthetic catalyst in phenylpropanoid assembly. PAL catalyses the non-oxidative deamination of L-phenylalanine to trans-cinnamic acid. PAL contains a catalytic Ala-Ser-Gly triad that is post-translationally cyclised. PAL is structurally similar to the mechanistically related histidine ammonia lyase (HAL; EC:, with PAL having an additional approximately 160 residues extending from the common fold [PMID: 15350127]. Catalysis in PAL may be governed by the dipole moments of seven alpha helices associated with the PAL active site. The cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) resides atop the positive poles of three helices, for increasing its electrophillicity. Plant and fungal PAL enzymes contain aa approximately 100-residue long C-terminal multi-helix domain, which might play a role in the rapid response of PAL in the regulation of phenylpropanoid biosynthesis by destabilising the enzyme [PMID: 16478474].

GO terms

Biological Process

GO:0006559 L-phenylalanine catabolic process

Molecular Function

GO:0016841 ammonia-lyase activity

Cellular Component

GO:0005737 cytoplasm

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.