A possible role in the regulation of primary amination for a complex of glutamine: α-Ketoglutarate amidotransferase and glutamate dehydrogenase in Escherichia coli

Both glutamine: α-ketoglutarate amidotransferase and glutamate dehydrogenase activities are obtained from Escherichia coli grown in minimal medium containing glucose and ammonia. These activities are not additive, suggesting an interaction between them. Normally both of these activities are equally inhibited by homoserine. In mutants resistant to homoserine inhibition both activities are affected in parallel. Furthermore, the ratio of the wild-type activities remains constant over a 30-fold range in purification. This evidence suggests that these activities are associated with a single complex. A possible role for this complex in the regulation of primary amination is discussed.