Thymidine kinase (TK) belongs to a group of enzymes such as dihydrofolate reductase, thymidylate synthase, and DNA polymerase that are involved in DNA synthesis and precursor production. High levels of these enzymes are present in proliferating cells, and low levels are found in resting cells, due to multiple regulatory mechanisms that ensure exclusive expression of these enzymes in replicating cells. TK is responsible for catalyzing the phosphorylation of thymidine, which functions as a part of the pyrimidine salvage pathway involved in DNA synthesis. The activities of enzymes such as TK are essential for the activation of several chemotherapeutically important nucleoside analogues that are administered as prodrugs.
Aliquot and store at -20°C. Avoid multiple freeze-thaw cycles.