ENZYMATIC SYNTHESIS OF DEOXYRIBONUCLEIC ACID. IV. LINKAGE OF SINGLE DEOXYNUCLEOTIDES TO THE DEOXYNUCLEOSIDE ENDS OF DEOXYRIBONUCLEIC ACID

Abstract

The reaction between deoxyribonucleic acid (DNA) and a single radioactive deoxynucleoside triphosphate resulted in a product whose radioactivity sediments at the same rate as the average DNA molecules; this indicates that the deoxynucleotide was incorporated into molecules which have the same size as DNA. Hydrolysis of the product to 3[image]-deoxynucleotides demonstrated the formation of 3[image],5[image]-phosphodiester linkages between the deoxynucleoside end of a DNA chain and the added deoxynucleotide. These studies further showed that only one or a very few molecules of the single deoxynucleoside triphosphate reacted with the end of each chain. The kinetics of hydrolysis of the product by snake venom phosphodiesterase, involving a sequential liberation of deoxnucleotides from the deoxynucleoside end of DNA chains, provided independent evidence that the deoxynucleoside triphosphate reacted with the deoxynucleoside end of a DNA chain.