Glutamine synthetase

Ammonium glutamate ligase ( short GS of outdated glutamine synthetase ) are called enzymes which transfer glutamate with ATP consumption ammonium to the amino acid. This results in the amino acid glutamine. Thus, they play an important role in the nitrogen metabolism of all living organisms, such as in the biosynthesis of glutamine, which in turn serves as a starting point in the synthesis of other compounds. The human GS is expressed only during early fetal life, a nitrogen assimilation as in bacteria does not take place, and man is dependent on amino acid intake. Mutations in GLUL gene can lead to very rare fetal systemic glutamine deficiency, which leads to severe damage and death of the newborn.

The GS is part of the so-called GS / GOGAT pathway ( Glutamin-Synthetase/Glutamin-Oxoglutarat-Aminotransferase ), an alternative way of assimilation of ammonia addition to the reaction by glutamate.

Classes

The GS is a common enzyme, the various forms can be divided into three classes:

  • Class 1: This type is found exclusively in prokaryotes and consists of twelve identical subunits of 50 kDa. The enzyme is subject to control by cumulative negative feedback, which is mediated by a variety of end products of glutamine metabolism. Further, the activity of the enzyme is controlled by reversible covalent modification. Here a specific tyrosine residue is adenylated each subunit of the enzyme, causing the inhibition is further enhanced by the negative feedback.
  • Class 2: In eukaryotes and some bacteria can find this type, which consists of ten identical subunits. In plants, several isoforms of glutamine synthetase class find 2
  • Class 3: GSIII has so far been found only in bacteria Bacteroides fragilis and Butyrivibrio fibrisolvens.

Catalyzed reaction

Glutamate ATP NH3 → glutamine ADP phosphate H2O

Swell

  • Ligase
  • Hereditary disease - associated protein
Human Genome Organisation Adenosine triphosphate Adenosine diphosphate
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