The DiviTum assay determines the enzymatic activity of thymidine kinase in serum samples. In the assay, thymidine is replaced by bromodeoxyuridine (BrdU), which is accepted by thymidine kinase as an analogous substrate:
BrdU + ATP → BrdU-monophosphate + ADP
Thymidine kinase activity determines the amount of BrdU built into a DNA strand. This BrdU incorporation is detected by an ELISA technique. The DiviTum™ technology amplifies the signal, enabling the assay to measure thymidine kinase activity with high sensitivity.
Thymidine kinase phossphorylate BrdU preparing it to be incorporated into DNA
The more thymidine kinase in the sample, the more BrdU-DNA is formed
Detection of incorporated is done by a BrdU-binding antibody conjugated to alkaline phosphatase. The color reaction is proportional to the level of activity of thymidine kinase in the sample