Nature of a Polynucleotide Required for Polyribonucleotide Formation from Adenosine Triphosphate with an Enzyme from Thymus Nuclei

Abstract

SUMMARY The polymerization of adenosine triphosphate (ATP) into polyadenylate chains of 50 to 100 nucleotides by an ATP poly- merase from calf thymus nuclei has been shown to depend upon the presence of polynucleotide primer, which can be isolated from a boiled extract of the purified enzyme. Treatment primer with pancreatic ribonuclease (RNase), Taka-Diastase T1 RNase and TQ RNase, snake venom phosphodiesterase, squid RNase, and A. agilis nuclease demonstrated that inactivation oc- curred only if the nuclease was capable of cleaving phosphodiester bonds between adenylate units. Purification of the enzyme raised the adenylate content of the polynucleotide component from 19y0 in the crude extract to 27 y0 in the purified enzyme and to 87% after removal of inactive polynucleotides by treatment with pancreatic RNase and Taka-Diastase T1 RNase. Poly- adenylate synthesized with polynucleotide phosphorylase was found to function as a primer for ATP polymerase, although the reaction differed in some details from that with the native primer. The conclusion was drawn that a long polyadenylate sequence occurred naturally in calf thymus nuclei as the primer for ATP polymerase. Acknowledgments-The authors were capably assisted in these experiments by Mrs. Elizabeth Burchard and Lana Price. REFERENCES