In enzymology, an aspartate—tRNA ligase is an enzyme that catalyzes the chemical reaction ATP + L-aspartate + tRNAAsp ⇌ {\displaystyle \rightleftharpoons } AMP + diphosphate + L-aspartyl-tRNAAspThe 3 substrates of this enzyme are ATP, L-aspartate, and tRNA, whereas its 3 products are AMP, diphosphate, and L-aspartyl-tRNA. Wikipedia