RT Journal Article SR Electronic T1 Fluorinated Pyrimidines JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 273 OP 280 VO 6 IS 3 A1 YOSHISADA FUJIWARA A1 TOSHIKAZU OKI A1 CHARLES HEIDELBERGER YR 1970 UL http://molpharm.aspetjournals.org/content/6/3/273.abstract AB 5-Trifluoromethyl-2'-deoxyuridine (F3TdR), a thymidine analogue, is incorporated into the DNA of HeLa and leukemia L5178Y cells in culture. Under conditions of synchrony induced by the production of thymidine deficiency and rescue by thymidine or a thymidine analogue, the addition of F3TdR does not permit any cell division, in contrast to thymidine, 5-bromo-2'-deoxyuridine, or 5-iodo-2'-deoxyuridine, which support cell division. However, F3TdR is incorporated into the cellular DNA, but to only about one-fourth the extent of thymidine. Alkaline sucrose gradient sedimentation revealed that the molecules of DNA containing F3TdR are smaller than normal DNA, suggesting that the rate of growth or joining of chains of DNA is inhibited as a result of the incorporation of the analogue. ACKNOWLEDGMENT We are grateful to Mrs. Barbara Lindsey for skilled technical assistance.