Asparagine synthetase catalyzes conversion of aspartate to asparagine:

Aspartate + ATP + NH3 (Glutamine) -> Asparagine + AMP + PPi + (Glutamate)

The reaction provides one way for cells to handle toxic ammonia and it also serves as a mechanism for making asparagine. Glutamine is a preferred substrate over ammonia.

Note that asparagine synthetase cleaves ATP to yield AMP + PPi, whereas glutamine synthetase (another enzyme for handling ammonia) yields ADP + Pi.