Exoribonuclease activity of purified reverse transcriptase preparations from retroviruses

Highly purified and commercially available preparations of reverse transcriptases from retroviruses contain a 3′ to 5′ exoribonuclease activity capable of hydrolyzing synthetic homopolyribonucleotides having a 3′ -OH end. The exoribonuclease activity of reverse transcriptase preparations from Rous associated virus-2 was further characterized. This exoribonuclease activity cleaves poly(C) and poly(U) exonucleolytically from the 3′-OH end to produce nucleoside 5′-phosphates. Poly(A), poly(G), circular polyribonucleotide, and double-stranded polyribonucleotide were not hydrolyzed by the activity. This is a novel type of exoribonuclease activity.