. "While this is the reaction that occurs in vertebrates during purine biosynthesis, two enzymes are required to carry out the same reaction in Escherichia coli, namely EC 6.3.4.18 and EC 5.4.99.18." . "5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole is not a substrate." . . . "Phosphoribosylaminoimidazole carboxylase" . "AIR carboxylase" . "1-(5-phosphoribosyl)-5-amino-4-imidazolecarboxylate carboxy-lyase" . "5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate carboxy-lyase" . "5-amino-1-ribosylimidazole 5-phosphate carboxylase" . "5-phosphoribosyl-5-aminoimidazole carboxylase" . "5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate = 5-amino-1-(5-phospho-D-ribosyl)imidazole + CO(2)." .