Metabolism of Glutamine

Abstract

The wide distribution of glutamine, glutamate and enzymes that catalyze reactions involving these suggests their participation significantly in metabolism, but also makes difficult the elucidation of specific biochemical pathways. There is evidence that glutamine is essential for the growth and maintenance of almost all living cells, but most of the available specific information deals with reactions involved in its interconversion with glutamate. Since the reactivity of glutamine in numerous processes is indicated in a variety of experimental approaches, the conversion of glutamate to glutamine may be a reaction of considerable importance in metabolism. The [omega]-amide group may serve as a source of N for several functions, including purine synthesis, urinary ammonia and urea synthesis. The [omega]-amide function is important in the transport of the glutamyl moiety across the cell membrane. These considerations and the fact that glutamine is a constituent of many proteins are sufficient to explain the apparently unique function of this amide in growth and metabolism, but there is good reason to suspect that it may participate in still other ways. Our present understanding of these phenomena probably represents only a small part of the information necessary for the final evaluation of the metabolic role of glutamine.