In enzymology, a polynucleotide 5'-hydroxyl-kinase (EC 2.7.1.78) is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are ATP and 5'-dephospho-DNA, whereas its two products are ADP and 5'-phospho-DNA.
Polynucleotide kinase is a T7 bacteriophage (or T4 bacteriophage) enzyme that catalyzes the transfer of a gamma-phosphate from ATP to the free hydroxyl end of the 5' DNA or RNA.
The resulting product could be used to end-label DNA or RNA, or in ligation reactions.
This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing groups (phosphotransferases) with an alcohol group as an acceptor.
The systematic name of this enzyme class is ATP:5'-dephosphopolynucleotide 5'-phosphotransferase.