Human Thymidine Kinase 1 protein, His and GST tag

Thymidine kinase 1 (TK1), is a human thymidine kinase. Thymidine kinase has been making a growing impact in the cancer research community. It has been found that elevated blood serum levels of TK-1 correlates with metastatic capabilities of the cancer and thereby can be used to detect malignant types of cancer, furthermore TK-1 has been found to show up in blood serum even before clinical symptoms even start to show. Besides, Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) has been identified as an interactor of TK1, thus a binding ELISA assay was conducted to detect the interaction of recombinant human TK1 and recombinant human GAPDH. Briefly, TK1 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to GAPDH-coated microtiter wells and incubated for 2h at 37ºC. Wells were washed with PBST and incubated for 1h with anti-TK1 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37ºC. Finally, add 50 μl stop solution to the wells and read at 450nm immediately. The binding activity of TK1 and GAPDH was in a dose dependent manner.