Stimulation and inhibition of deoxyribonucleic acid nucleotidyltransferase by oligodeoxyribonucleotides

The importance of the physicochemical condi- tion of primer DNA in the DNA nucleotidyl- transferase (polymerase) system (deoxynucleoside triphosphate-DNA deoxynucleotidyltransferase, EC 2.7.7.7) from mouse Landschutz ascites- tumour cells has been emphasized by Keir, Binnie & Smellie (1962). The ability of DNA to prime the reaction was enhanced by 60 % after limited pre- treatment with pancreatic deoxyribonuclease, an effect which was suggested to be the consequence of increased availability of 3'-hydroxy-terminal groups for nucleophilic attack at the ac-phosphate group of deoxyribonucleoside triphosphates. A more de- tailed investigation of the phenomenon has now been undertaken and is described in this paper, with kinetic studies of the action of DNA nucleo- tidyltransferase.