 Adenylosuccinate lyase in humans and "Bacillus subtilis" can be competitively inhibited by the substrate analog adenosine phosphonobutyric acid 2’(3’), 5’-diphosphate (APBADP).APBADP is a competitive inhibitor for both of the reactions catalyzed by adenylosuccinate lyase, and kinetic studies with APBADP show that the substrates for both reactions use the same active site.In the ASL-catalyzed reaction splitting adenylosuccinate into adenosine monophosphate (AMP) and fumarate, the AMP must rotate slightly after the reaction is complete and before fumarate is released in order for both products to fit in the active site.