Adenylosuccinate lyase
![](/Images/godic/202412/18/ASL_active_sites4622.png")
![This flow chart shows the steps in the biosynthesis of AMP.Steps in green show steps catalyzed by ASL Steps in red show the dephosphorylation of ASL's substrates](/Images/godic/202412/18/Purine_biosynthesis4622.jpg")
![ASL cleaves SAICAR into AICAR and fumarate, and adenylosuccinate into AMP and fumarate. This figure was inspired by one from a paper by Toth and Yeates.[1]](/Images/godic/202412/18/Overall_reactions_catalyzed_by_adenylosuccinate4622.jpg")
![ASL's mechanism of action. First the acid deprotonates the β-carbon, then a carbanion forms and is resonance stabilized, lastly nitrogen accepts a proton and the C-N bond is cleaved.This figure was inspired by a paper by Tsai et al.[5]](/Images/godic/202412/18/Reaction_mechanism_of_ASL4622.jpg")
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.