Ribonuclease H: An Enzyme Degrading the RNA Moiety of DNA‐RNA Hybrids

Abstract

Extracts from calf thymus contain an enzyme degrading the RNA moiety of DNA‐RNA hybrids. An assay for this enzyme and several characteristics of the enzyme reaction are described. The specificity of the enzyme for DNA‐RNA hybrids is indicated by several lines of evidence: The RNA of the hybrid is rendered resistant to the action of this enzyme upon heating. Nucleic acids other than DNA‐RNA hybrids are not affected to a comparable degree. The enzyme rapidly degrades polyribouridylic acid if it is hybridized to polydeoxyriboadenylic acid, but not if it is hybridized to polyriboadenylic acid. Experiments with double labelled DNA‐RNA hybrids show that specifically the RNA moiety of the hybrid and not the DNA is attacked by the enzyme. Copyright © 1970, Wiley Blackwell. All rights reserved