In enzymology, a leucyltransferase (EC 2.3.2.6) is an enzyme that catalyzes the chemical reaction

L-leucyl-tRNA + protein tRNA + L-leucyl-protein

Thus, the two substrates of this enzyme are L-leucyl-tRNA and protein, whereas its two products are tRNA and L-leucyl-protein.

This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-leucyl-tRNA:protein leucyltransferase. Other names in common use include leucyl, phenylalanine-tRNA-protein transferase, leucyl-phenylalanine-transfer ribonucleate-protein, aminoacyltransferase, and leucyl-phenylalanine-transfer ribonucleate-protein transferase.

As of late 2007, three structures have been solved for this class of enzymes, with PDB accession codes 2CXA, 2DPS, and 2DPT.

• Leibowitz MJ, Soffer RL (1969). "A soluble enzyme from Escherichia coli which catalyzes the transfer of leucine and phenylalanine from tRNA to acceptor proteins". Biochem. Biophys. Res. Commun. 36 (1): 47–53. doi:10.1016/0006-291X(69)90647-0. PMID 4894363.
• Leibowitz MJ, Soffer RL (1970). "Enzymatic modification of proteins. 3. Purification and properties of a leucyl, phenylalanyl transfer ribonucleic acid protein transferase from Escherichia coli". J. Biol. Chem. 245 (8): 2066–73. doi:10.1016/S0021-9258(18)63207-7. PMID 4909560.
• Soffer RL (1973). "Peptide acceptors in the leucine, phenylalanine transfer reaction". J. Biol. Chem. 248 (24): 8424–8. doi:10.1016/S0021-9258(19)43150-5. PMID 4587124.