Deoxycytidine phosphates formation

Deoxycytidylate deaminase is evidently absent from a number of bacterial species, includii E. coli, S. typhimvrium, and B. subtilts. Accordingly, in these cells the deoxycytidine phosphates do not contribute to the synthesis of the thymidine phosphates in the manner described above for animal cells. However, enzymes catalyzing the deamination of dCTP have been demonstrated in E. ccU and S. typhimvrium the latter enzyme has been partly purified and shown to deaminate dCTP, but not CTP, dCDP, CDP, eytidylate, nor deoxycytidine (26). The formation of dUTP by this enzyme, followed by the action of the specific dUTP pyrophosphatase, would consitutue a route for the formation of deoxyuridylate ... 

As described before, a smaller substituent at the 2 -P position of 2 -deoxycytidine is tolerant only for cytotoxicity. Introduction of an electron-withdrawing group into the 2 -P position would increase the acidity of the 2 -a proton. If such a nucleoside is enzymatically phosphorylated and incorporated into DNA molecules, the electron-withdrawing group becomes P to the phosphate diester in the DNA molecule. In this case, P-elimination would produce (i) DNA strand-breaks or (ii) abasic site formation as illustrated in Fig. S. Together with this hypothesis, the nucleoside 5 -polyphosphates would also inhibit ribonucleotide reductase and/or DNA polymerases. Since strand-breaks in DNA by radiation thenq)y have been hypothesized to produce tumor cell death, it is worth examining whether the nucleoside... 

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