The degradation of acidsoluble collagen by rat-liver preparations.

nucleotide was increased, and, assuming that the product was derived from oligonucleotides and deoxyribonucleoside triphosphates, the synthesis amounted to 74% of the deoxyribonucleic acid primer. 4. The nucleotidyltransferase was inhibited and the lag phase extended by 3'-phosphoryl-terminal oligonucleotides from a splenic-deoxyribonuclease digest of deoxyribonucleic acid. 5. The compounds obtained by removal of terminal phosphoryl groups from the 3'and 5'phosphoryl-terminal oligonucleotides by bacterial alkaline phosphatase abolished the lag phase, and they supported synthesis at a level similar to that observed under standard assay conditions. 6. It was concluded that 5'-phosphoryl-terminal oligonucleotides associate by specific hydrogenbonding with single-stranded regions of the deoxyribonucleic acid primer and stimulate synthesis of polydeoxyribonucleotide by providing 3'-hydroxyl groups to initiate polymerization along the adjacent single-stranded template. The 5'-phosphorylterminal group on these oligonucleotides is partly responsible for the stimulation observed. Inhibition by 3'-phosphoryl-terminal oligonucleotides is attributable to competition with 3'-hydroxyl groups formed on the deoxyribonucleic acid primer by deoxyribonuclease during the nucleotidyltransferase assay, and the lag phase observed under standard conditions is a period of production of stimulatory end groups in the deoxyribonucleic acid primer.