Glutamate synthase and nitrogen assimilation

The assimilation of ammonia by a wide variety of organisms is the primary route for the introduction of nitrogen into the biosphere. The assimilatory enzymes glutamine synthetase and glutamate synthase catalyze reactions that convert a-ketoglutarate and ammonia to glutamate, which is then used in a wide variety of biosynthetic reactions. These enzymes also play a major role in the reassimilation of ammonia derived from photorespiration in C-3 plants. Recent biochemical, molecular and genetic studies are leading to a better understanding of the factors that determine the activity and function of glutamate synthase.