It was shown that the crude extracts of Ehrlich ascites carcinoma which contain the activities of thymidine kinase and thymidine monophosphate kinase and diphosphate kinase can effectively catalyze the synthetic reaction of

3

H-TTP from the substracte—

3

H-thymidine (TdR). The conversion rate of TdR to TTP by these extracts was more than 75%

higher than those by rat regenerating liver and yeast. A method for complete separation of

3

H-TdR and

3

H-TTP was established using DEAE-Sephadex A-25 column chromatography

and then eluting with ammonium bicarbonate. The product was salt free. The optimum conditions for the reaction were ATP and enzyme Mg

++

(11µmol each)

reaction time 2hr. at 37℃ and enzyme protein

less than 5mg per milliliter reaction volume.