aBoth the Omniscript and the Sensiscript RTases retain RNase H activity. They are different from the RTases of Moloney murine leukaemia virus (MMLV) or avian myeloblastosis virus (AMV) origin (Sensiscript and Omniscript reverse transcriptase handbook, Qiagen). The Sensiscript RTase is a recombinant heterodimeric enzyme expressed in E. coli. TheSuperScript II and SuperScript III RTases are an engineered version of MMLV RTase with reduced RNase H activity and increased thermal stability. The PowerScript RTase is a point mutant of MMLV RTase, which lacks the RNase H enzyme and retains wild-type polymerase activity, thus being able to synthesise longer cDNA fragments .