Competitive inhibition of glutamate dehydrogenase reaction

Irrespective of their pyridine nucleotide specificity, all glutamate dehydrogenases share a common chemical mechanism that involves an enzyme bound ‘iminoglutarate’ intermediate. Three compounds, structurally related to this intermediate, were tested for the inhibition of purified NADP‐glutamate dehydrogenases from two Aspergilli, as also the bovine liver NAD(P)‐glutamate dehydrogenase. 2‐Methyleneglutarate, closely resembling iminoglutarate, was a potent competitive inhibitor of the glutamate dehydrogenase reaction. This is the first report of a non‐aromatic structure with a better glutamate dehydrogenase inhibitory potency than aryl carboxylic acids such as isophthalate. A suitably located 2‐methylene group to mimic the iminium ion could be exploited to design inhibitors of other amino acid dehydrogenases.