EFFECT OF CYTOSINE ARABINOSIDE 5'-TRIPHOSPHATE ON MAMMALIAN DNA POLYMERASE

Cytosine arabinoside 5′-triphosphate (araCTP) produced an inhibition of a partially purified DNA polymerase obtained from calf thymus. The purified DNA polymerase catalyzed the incorporation of 3H-araCTP into an acid insoluble product (DNA) in the presence of dATP, dGTP, dTTP, MgCl2, and denatured DNA. The addition of dCTP to the reaction mixture partially reversed the inhibition of DNA polymerase by araCTP and decreased the incorporation of 3H-araCTP into DNA. About 90% of the radio-activity in the DNA product after treatment with micrococcal nuclease and spleen phosphodiesterase was released as 3H-cytosine arabinoside, suggesting that most of the incorporation was at the 3′-hydroxyl terminal end and not within the polydeoxynucleotide chain. © 1969.