InterPro domain: IPR000031

The novo purine biosynthesis proceeds by two divergent paths. In bacteria, yeasts, and plants, 5-aminoimidazole ribonucleotide (AIR) is converted to 4-carboxy-AIR (CAIR) by two enzymes: N5-carboxy-AIR (N5-CAIR) synthetase (PurK) and N5-CAIR mutase (class I PurE). In animals, the conversion of AIR to CAIR requires a single enzyme, AIR carboxylase (class II PurE) [ 1 ]. Class I and class II PurEs are mechanistically related but bind different substrates. In yeast and plants PurE is found in PurK-class I PurE fusion proteins, known as ADE2 [ 2 , 3 ], while animal class II PurEs are found in PurC-PurE fusion proteins, also known as ADE2 or PAICS [ 4 ].

1. Reactions catalyzed by 5-aminoimidazole ribonucleotide carboxylases from Escherichia coli and Gallus gallus: a case for divergent catalytic mechanisms. Biochemistry 33, 11927-34
2. Structural organization of de novo purine biosynthesis enzymes in plants: 5-aminoimidazole ribonucleotide carboxylase and 5-aminoimidazole-4-N-succinocarboxamide ribonucleotide synthetase cDNAs from Vigna aconitifolia. Plant Mol. Biol. 24, 389-95
3. Biochemical role of the Cryptococcus neoformans ADE2 protein in fungal de novo purine biosynthesis. Arch. Biochem. Biophys. 351, 123-34
4. Carboxylases in de novo purine biosynthesis. Characterization of the Gallus gallus bifunctional enzyme. Biochemistry 33, 11917-26