Simplified synthesis of mono(4-aminophenyl)-3'-thymidilic acid ester used as thymidine kinase specific ligand for affinity chromatography

Four deoxynucleoside kinase activities from Drosophila melanogaster are contained within a single monomeric enzyme, a new multifunctional deoxynucleoside kinase

In mammalian cells, there are three pyrimidine nucleoside salvage enzymes with the capacity to phosphorylate all four deoxynucleosides, the two thymidine kinase isoenzymes, TK1 and TK2, and the deoxycytidine kinase, dCK. TK1 is cell cycle-regulated; TK2 is expressed constitutively and can phosphorylate deoxycytidine to the same extent as thymidine. dCK phosphorylates deoxycytidine, deoxyadenosine, and deoxyguanosine, but not thymidine. In addition, the three kinases can phosphorylate a number of medically important analogs. In cultured Drosophila melanogaster embryonic cells, only one pyrimidine deoxynucleoside kinase was present. This kinase was purified and showed a broad substrate specificity, since it was able to phosphorylate all four deoxynucleosides with high efficiency, as compared with the kinases in mammalian cells. Additionally, a number of nucleoside analogs such as arabinofuranosyl pyrimidines, deoxyuridine, and 5'-fluorodeoxyuridine, were phosphorylated. There was negligible 3'-azidothymidine and no dTMP phosphorylation. The enzyme was active as a monomer of about 30 kDa. We suggest the name D. melanogaster deoxynucleoside kinase for this multifunctional kinase. The substrate specificity, size, and other characteristics show that this enzyme is more related to human TK2 than to the other mammalian deoxyribonucleoside kinases, but is unique with respect to the capacity to phosphorylate all four deoxynucleosides.

Ligands for the affinity chromatography of mammalian thymidine kinase. 1: Strategy, synthesis and evaluation

Selected thymidine derivatives were synthesized with various spacers and fixed as model compounds at position N-3', C-5, C-3' and C-5', respectively, to simulate the preparation of an affinity gel matrix. Compounds 3, 6, 7 and 9 were evaluated for their effect on pure human cytosolic thymidine kinase (TK). All four compounds showed competitive inhibition with respect to thymidine, with Ki-values between 80 and 1000 microM. In the same positions as the model compounds were bound to the spacers thymidine derivatives were coupled with different Sepharose gel matrices. These affinity matrices were tested for isolation of thymidine kinase out of placental enzyme material. Except for one matrix, more than 98% of the applied activity was retained by the affinity matrices tested. The strongest binding to the enzyme resulted from a fixation at C-5' of the thymidine molecule to the gel matrix.