6-Diazo-5-oxo-L-nor-Leucine (DON) is a glutamine analog that inhibits glutaminases (Ki = 6 μM) and other glutamine-utilizing enzymes, including cytidine triphosphate synthase (CTPS), which uses glutamine in the synthesis of CTP. DON is commonly used in cells or tissues but its use in whole animals is limited by its teratogenicity.
