An essentially pure preparation of thermostable RNase H isolated from Thermus flavus is disclosed. In one preferable form of the invention, the RNase H is capable of biological activity after incubation at temperatures equal to or greater than 70.degree. C. for at least ten minutes. The present invention...http://www.google.de/patents/US5500370?utm_source=gb-gplus-sharePatent US5500370 - Thermostable ribonuclease H and genetic constructs therefore