Aspartate ammonia-lyase  In enzymology, an aspartate ammonia-lyase () is an enzyme that catalyzes the chemical reaction  Hence, this enzyme has one substrate, L-aspartate, and two products, fumarate and NH3. The reaction is the basis of the industrial synthesis of aspartate. This enzyme belongs to the family of lyases, specifically ammonia lyases, which cleave carbon-nitrogen bonds. The systematic name of this enzyme class is L-aspartate ammonia-lyase (fumarate-forming). Other names in common use include aspartase, fumaric aminase, L-aspartase, and L-aspartate ammonia-lyase. This enzyme participates in alanine and aspartate metabolism and nitrogen metabolism. As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .