Utilization of 5-fluoro-2'-deoxyuridine triphosphate and 5-fluoro-2'-deoxycytidine triphosphate in DNA synthesis by DNA polymerases alpha and beta from calf thymus.

Abstract

Chemically synthesized 5-fluoro-2'-deoxyuridine 5'-triphosphate and 5-fluoro-2'-deoxycytidine 5'-triphosphate were used efficiently as substitutes for DNA synthesis catalyzed by DNA polymerases alpha or beta from calf thymus. 5-fluoro-2'-deoxyuridine 5'-triphosphate and 5'-fluoro-2'-deoxycytidine 5'-triphosphate were incorporated into DNA in place of deoxythymidine 5'-triphosphate and deoxycytidine 5'-triphosphate, respectively. The incorporated pyrimidine analogs supported further elongation of DNA. The apparent Km's for 5-fluorodeoxyuridine 5'-triphosphate in the reaction of DNA polymerases alpha and beta were 4.3 and 15.4 microM, while those of 5-fluorodeoxycytidine 5'-triphosphate with DNA polymerases alpha and beta were 7.7 and 8.8 microM, respectively, which are comparable to Km's for natural substrates. These results suggest the new possibility that the fluorinated pyrimidines are incorporated into DNA via their triphosphate forms to exhibit their cytostatic actions.