nucleotidyltransferases. Enzymes (EC class 2.7.7) transferring nucleotide residues (nucleotidyls) from nucleoside di- or triphosphates into dimer or polymer forms. Some nucleotidyltransferases bear specific names (e.g., adenylyltransferases), or trivial names indicating the linkage hydrolyzed in the synthesis (pyrophosphorylases, phosphorylases), or names of the material synthesized (RNA or DNA polymerase). [ ]