Adenylosuccinate lyase (or adenylosuccinase) is an enzyme that in humans is encoded by the ADSL gene. Adenylosuccinate lyase converts adenylosuccinate to AMP and fumarate as part of the purine nucleotide cycle. ASL catalyzes two reactions in the purine biosynthetic pathway that makes AMP; ASL cleaves adenylosuccinate into AMP and fumarate, and cleaves SAICAR into AICAR and fumarate. Point mutations in adenylosuccinate that cause lowered enzymatic activity cause clinical symptoms that mark the condition adenylosuccinate lyase deficiency.