Characterization of human thymidine kinase 2 activity

2014-07-23Although radiolabeled TdR has been used in vitro for measurement of rates of DNA synthesis, rapid in vivo catabolism has limited its utility as a radiotracer targeted at measuring cellular proliferation in vivo. In recent years, development of PET radiotracer has focused on thymidine (TdR) analogs for imaging cell proliferation that are resistant to metabolism in vivo. Thymidine kinases are key enzymes in the salvage pathway of TdR synthesis and have been the targets for designing nucleoside analogues for monitoring cellular proliferation. In this study, a human mitochondrial thymidine kinase (hTK2) was expressed in an attempt to characterize in detail its kinetic parameters. The kinetic data from our experiments were significantly different from previously published data, as well as comparative studies. For future studies the effects of the fusion proteins on the activity of the hTK2 has to be further investigated. Nonetheless, the data presented in this thesis lays a methodological platform for the future screening of novel nucleoside analogues that can be used as radiotracers targeted to the measurement of cellular proliferation in tumors