Of the multiple RNases H in mammals, RNase HI is the major enzyme and shows increased activity during DNA replication. It shows more homology to the RNase HII of Escherichia coli.Of the multiple RNases H in mammals, RNase HI is the major enzyme and shows increased activity during DNA replication. It shows more homology to the RNase HII of Escherichia coli.Of the multiple RNases H in mammals, RNase HI is the major enzyme and shows increased activity during DNA replication. It shows more homology to the RNase HII of Escherichia coli.