What is the function of glutamine synthetase?

Glutamine synthetase (GS) plays a critical role in the brain to detoxify ammonia and regulate concentration and compartmentalization of neurotransmitter pools of glutamate and gamma-aminobutyric acid (GABA).

What happens during glutamine synthetase?

The enzyme glutamine synthetase is a key enzyme controlling the use of nitrogen inside cells. Glutamine, as well as being used to build proteins, delivers nitrogen atoms to enzymes that build nitrogen-rich molecules, such as DNA bases and amino acids.

Why is glutamine synthetase important?

Glutamine synthetase assimilates ammonium into amino acids, thus it is a key enzyme for nitrogen metabolism. In this way, cytosolic glutamine synthetase is crucial for the remobilization of protein-derived nitrogen.

What activates glutamine synthetase?

Mechanism. GS catalyzes the ATP-dependent condensation of glutamate with ammonia to yield glutamine. The hydrolysis of ATP drives the first step of a two-part, concerted mechanism.

What class of enzyme is glutamine synthetase?

Enzyme
Glutamine synthetase/Classification

How do you regulate glutamine synthetase?

Detailed studies of the glutamine synthetase (GS) in Escherichia coli and other bacteria have shown that the activity of this enzyme is regulated by at least five different mechanisms: (i) cumulative feedback inhibition by multiple end products of glutamine metabolism, (ii) interconversion between taut and relaxed …

What inhibits glutamine synthetase?

Glutamine synthetase activity in E. coli is subject to inhibition by seven different end products of glutamine metabolism, namely, by tryptophan, histidine, carbamyl-phosphate, CTP, AMP, glucose-6-phosphate, and NAD+, and also by serine, alanine, and glycine.

What is plant glutamate?

Glutamate occupies a central position in amino acid metabolism in plants. The acidic amino acid is formed by the action of glutamate synthase, utilizing glutamine and 2-oxoglutarate. However, glutamate is also the substrate for the synthesis of glutamine from ammonia, catalysed by glutamine synthetase.

Which step uses the enzyme glutamine synthetase?

Glutamine synthetase (GS) (EC 6.3. 1.2) is a key enzyme in the first step of NH4 + assimilation, which is responsible for the synthesis of glutamine. GS isozymes have different metabolic roles, and their activities vary during plant development in different organs and cell types.

Do humans have glutamine synthetase?

In humans, glutamine synthetase is a ubiquitous enzyme found at high concentration in the liver, brain and muscle. In liver it is localized to a subpopulation of perivenous parenchymal cells and in brain it is mainly found in the cytoplasm of astrocytes.

What part of the brain produces glutamate?

Glutamate is synthesized in the central nervous system from glutamine as part of the glutamate–glutamine cycle by the enzyme glutaminase. This can occur in the presynaptic neuron or in neighboring glial cells.

How is glutamine synthetase expressed in endothelial cells?

Glutamine synthetase, encoded by the gene GLUL, is an enzyme that converts glutamate and ammonia to glutamine. It is expressed by endothelial cells, but surprisingly shows negligible glutamine-synthesizing activity in these cells at physiological glutamine levels. Here we show in mice that genetic d …

Are there any effective treatments for glutamine synthetase?

There are no effective treatments. Glutamine synthetase (GS), a Mn-dependent enzyme, plays an important role in metabolizing nitrogen by catalyzing the reaction of condensation of glutamate and ammonia to form glutamine. An increased expression of GS mRNA has been observed due to Mn-potentiated cellular overload of iron (Zheng et al., 1999 ).

Where is the binuclear metal binding site in glutamine synthetase?

Schematic view of the binuclear metal binding site in glutamine synthetase. The proposed mechanism involves the binding of ATP adjacent to one Mn 2+ and glutamate adjacent to the other Mn 2+ followed by glutamate attack on the γ-phosphorus atom of ATP, producing a γ-glutamyl phosphate intermediate and releasing ADP.

How is glutamine produced in the mitochondria?

Glutamine is produced by glutamine synthetase, a mitochondrial enzyme that catalyzes the formation of the amide bond between ammonia and glutamate. This reaction requires energy released by hydrolysis of ATP into ADP and P i. The reaction is practically irreversible.