Asparagine synthase (glutamine hydrolysing)

Asparagine synthase (glutamine-hydrolysing) (EC 6.3.5.4, asparagine synthetase (glutamine-hydrolysing), glutamine-dependent asparagine synthetase, asparagine synthetase B, AS, AS-B) is an enzyme with systematic name L-aspartate:L-glutamine amido-ligase (AMP-forming). This enzyme catalyses the following chemical reaction

ATP + L-aspartate + L-glutamine + H₂O ⇌ AMP + diphosphate + L-asparagine + L-glutamate (overall reaction)(1a) L-glutamine + H₂O ⇌ L-glutamate + NH₃(1b) ATP + L-aspartate + NH₃ ⇌ AMP + diphosphate + L-asparagine

The enzyme from Escherichia coli has two active sites6].