Aminoacyltransferases (EC 2.3.2) are acyltransferase enzymes which act upon an amino group. For instance, aminoacyl tRNA synthetases attach an aminoacid through esterification to their corresponding tRNA. The activation of amino acids with aminoacyl-tRNA synthetase requires hydrolysis of ATP to AMP plus PPi. The aminoacyl-tRNA molecule has close relationships with elongation factors like EF-Tu.
Peptidyl transferases are also a type of aminoacyltransferase that catalyze the formation of peptide bonds, as well as the hydrolytic step that leads to the release of newly synthesized proteins off the tRNA.