| Comments |
This enzyme is a member of the aromatic amino acid lyase family, other members of which are EC?4.3.1.3?(histidine ammonia-lyase), EC?4.3.1.24?(phenylalanine ammonia-lyase) and EC?4.3.1.25?(phenylalanine/tyrosine ammonia-lyase). The enzyme contains the cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO), which is common to this family [1]. This unique cofactor is formed autocatalytically by cyclization and dehydration of the three amino-acid residues alanine, serine and glycine [3]. The enzyme is far more active with tyrosine than with phenylalanine as substrate, but the substrate specificity can be switched by mutation of a single amino acid (H89F) in the enzyme from the bacterium?Rhodobacter sphaeroides?[1,2]. |
