TABLE 4 : Amino acid positions mentioned in 48and adjacent amino acid positions that occur in at least 50% of the 44 PURase homologues from the LED (superfamily 13). Position numbers refer to PudA from Delftia acidovorans , i.e., Uniprot identifier Q9WX47. Similar amino acid residues occurring in less than 50% of the sequences are indicated in brackets for comparison. Positions of a putative substrate binding region are listed as supporting information for comparison (Table S5 ).