Important purine precursor. Synthesis by enzymic reaction according to the equation AIR + ATP + aspartic acid + CO2 → SAICAR + ADP + orthophosphate: Lukens, Buchanan, J. Biol. Chem. 234, 1791 (1959). Production by adenine-requiring mutants of Bacillus subtilis: Ohmura et al., US 3280007 (1966 to Takeda). Synthesis of SAICAR and derivatives: Burrows, Shaw, J. Chem. Soc. C 1967, 1088; Burrows et al., ibid. 1968, 40.