|The TyrA family includes enzymes with four specificities. PapC participates in antibiotic synthesis and utilizes the 4-amino derivative of prephenate (PPA) as substrate.
It can be recognized by its lack of an otherwise invariant residue that interacts with the 4-hydroxy substituent of the cyclohexadienyl substrate in the other three classes.
The remaining three classes are alternative dehydrogenase reactions of TYR biosynthesis. TyrAa and TyrAp are specific for AGN and PPA, respectively.
TyrAc enzymes have broad specificity and can recognize both AGN and PPA to various extents. The latter three classes do not separate into discrete groupings, and no obvious discriminating motifs have been found.
However, profile HMMs that are provided as a tool here have tentative value for prediction of substrate specificity.
A distinct variation of the TyrAc class, denoted as TyrAc_Δ, possesses deletion indels within the catalytic core region.