T1 - Utilization of labeled thymidine in DNA synthesis
Synthesis and release of thymidine by macrophages.
However, incorporation of bromodeoxyuridine into DNA is a lethal event. Thus, thymidine kinase deficiency leads to a BrdUrd-resistant phenotype. Because most large DNA viruses encode a thymidine kinase, this is a useful system for manipulating viral genes, for example, the use of vaccinia virus as a vector in the generation of multivalent vaccines (7).
US4914233A - Synthesis of beta-thymidine - Google …
On the other hand, one can select for the presence of active salvage enzymes. The best example is the use of "HAT medium" in somatic cell genetic analysis and in preparing monoclonal antibodies. These techniques involve fusing cells of different origins and culturing in HAT medium to select for those cells that have undergone fusion. HAT is an acronym for the medium’s constituents,— hypoxanthine, aminopterin, and thymidine. Aminopterin inhibits dihydrofolate reductase, blocking the synthesis of tetrahydrofolate needed for de novo synthesis of purine nucleotides and thymidine nucleotides. Thus, cells can grow in HAT medium only if they express active thymidine kinase and HGPRT, for salvage synthesis of thymidine and purine nucleotides, respectively. In monoclonal antibody production, one of the cell lines to be fused lacks thymidine kinase, and the other lacks HGPRT. Thus, only cells resulting from a fusion event have functional copies of both enzymes and can grow.
DNA synthesis (Thymine --> Thymidine ..
“Synthesis and Evaluation of Thymidine-5 ’-O-monophosphate Analogues as Inhibitors of Mycobacterium Tuberculosis Thymidylate Kinase.” 12 (19): 2695–2698.
Pyrimidine salvage is catalysed by thymidine kinase.
It is useful to begin our survey of deoxyribonucleotide biosynthesis by considering the processes through which the chemical differences between DNA nucleotides and RNA nucleotides arise. The methyl group of thymine, which distinguishes it from uracil, arises through the transfer of a single-carbon functional group to a uracil nucleotide, catalyzed by thymidylate synthase. The presence of 2-deoxyribose as the sugar in DNA nucleotides rather than the ribose found in RNA comes about through reduction of the ribose sugar on a ribonucleotide substrate (see Ribonucleotide Reductases). Some aerobic bacteria and all anaerobic microorganisms studied carry out this reduction at the ribonucleoside triphosphate (rNTP) level. In all other organisms studied, however, the substrates for ribonucleotide reductase are the ribonucleoside 5′ -diphosphates (rNDPs). Whether a particular reductase acts on rNDPs or rNTPs, a single enzyme reduces all four ribonucleotide substrates. Accordingly, the enzyme interacts with allosteric modifiers to ensure that the four DNA precursors are produced at rates commensurate with the base composition of the organism’s genome. In this article, we will describe the predominant pathways to dNTPs that begin with reduction of rNDPs to deoxyribonucleoside diphosphates (dNDPs). These pathways are summarized in Figure 1.