 J. G. Stavrianopoulos (RNase H researcher)

J. G. Stavrianopoulos is the first author of a 1973 study purifying and characterizing calf-thymus Ribonuclease H. The investigators enriched the activity more than 3000-fold, then tested the preparation on defined RNA-DNA hybrids and on other RNA material. Activity required suitable metal ions, including magnesium or manganese under the reported conditions.^[ref]

The preparation cleaved the tested RNA-DNA hybrids but did not attack ribosomal RNA. A negative substrate result is informative here: the name ribonuclease alone does not specify which molecular arrangement an enzyme recognizes. Comparing paired nucleic-acid substrates with an RNA preparation lacking the DNA partner helped characterize specificity rather than merely establishing that some cleavage occurred.^[ref]