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