Argininosuccinate synthase

![Reaction catalyzed by argininosuccinate synthetase. Adapted from Goto et al. 2003.[2]](/uploads/202412/21/WikiChemdraw4913.png)


Argininosuccinate synthase or synthetase (ASS; EC6.3.4.5) is an enzyme that catalyzes the synthesis of argininosuccinate from citrulline and aspartate.
ASS is responsible for the third step of the urea cycle and one of the reactions of the citrulline-NO cycle.