In enzymology, an aspartate—ammonia ligase (ADP-forming) (EC 6.3.1.4) is an enzyme that catalyzes the chemical reaction

ATP + L-aspartate + NH₃ ${\displaystyle \rightleftharpoons }$ ADP + phosphate + L-asparagine

The 3 substrates of this enzyme are ATP, L-aspartate, and NH₃, whereas its 3 products are ADP, phosphate, and L-asparagine.

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-ammonia (or amine) ligases (amide synthases). The systematic name of this enzyme class is L-aspartate:ammonia ligase (ADP-forming). Other names in common use include asparagine synthetase (ADP-forming), and asparagine synthetase (adenosine diphosphate-forming). This enzyme participates in nitrogen metabolism.

• Nair PM (September 1969). "Asparagine synthetase from gamma-irradiated potatoes". Archives of Biochemistry and Biophysics. 133 (2): 208–15. doi:10.1016/0003-9861(69)90447-0. PMID 5820987.