Regulation of glutamate synthase from Bacillussubtilis by Glutamine

Abstract Glutamate synthase, an important enzyme in the assimilation of ammonia, was measured in cultures of Bacillus subtilis grown with different nitrogen sources. An attempt was made to correlate the specific activity to the intracellular levels of five metabolites of glutamate metabolism: aspartate, glutamate, glutamine, alanine and NH 4 + . An inverse relationship was found between the activity of glutamate synthase and the pool level of glutamine. We propose that the intracellular concentration of glutamine is an important element in controlling the level of glutamate synthase.