Specific action of adenine as a feedback inhibitor of purine biosynthesis.

Purines can prevent the formation of aminoimidazole precursors which are accumulated by bacterial mutants genetically blocked in purine biosynthesis. If the block does not interfere with interconversions among adenine, guanine, hypoxanthine and xanthine, then any of the purines can act as a feedback inhibitor. If conversion of the other purines to adenine is prevented, then adenine becomes a specific requirement for inhibition; this indicates that feedback control operates at a level involving adenine or one of its congeners.