<p>The amidotransferase family of enzymes utilises the ammonia derived from the hydrolysis of glutamine for a subsequent chemical reaction catalyzed by the same enzyme. The ammonia intermediate does not dissociate into solution during the chemical transformations [<cite idref="PUB00006448"/>].GMP synthetase is a glutamine amidotransferase from the <i>de novo</i> purine biosynthetic pathway. The C-terminal domain is specific to the GMP synthases <db_xref db="EC" dbkey="6.3.5.2"/>. In prokaryotes this domain mediates dimerisation. Eukaryotic GMP synthases are monomers. This domain in eukaryotes includes several large insertions that may form globular domains [<cite idref="PUB00003933"/>].</p>