T4 Polynucleotide Kinase catalyzes the transfer and exchange of Pi from the γ position of ATP to the 5´ hydroxyl terminus of polynucleotides (double- and single-stranded DNA and RNA), as well as nucleoside 3´ monophosphates

The T4 Polynucleotide Kinase also catalyzes the removal of 3´ phosphoryl groups from 3´ phosphoryl polynucleotides, deoxy­nucleoside 3´ monophosphates and deoxynucleoside 3´ diphosphates.