Developmental changes of two distinct ribonuclease H activities from rat brain and characterization of these enzymes

The specific activities of both Mg2+- and Mn2+-dependent ribonucleases H (RNAase H) from rat cerebella increased up to approx. the 6th day after birth and then decreased in adult rats. Those isolated from the non-cerebellar part decreased gradually toward adult levels after birth. The two enzymes could be separated by phosphocellulose chromatography. They can be distinguished from one another by their ionic requirement, molecular weight, sedimentation coefficient, optimal pH, sensitivity to the -SH reagent, and the effects of salt, polyamine and pyrophosphate. Both enzymes liberate a mixture of oligonucleotides from RAN substrates, with 5'-phosphate and 3'-hydroxyl termini.