MMLV (Moloney Murine Leukemia Virus) Reverse Transcriptase is a DNA polymerase that synthesizes a complementary DNA strands from single-stranded RNA, DNA, or an RNA-DNA hybrid as a template. This recombinant enzyme was purified from E.coli, which carried a modified MMLV-RT gene. Compared to AMV Reverse Transcriptase, this enzyme has a much weaker 5' - 3' ribonuclease H activity, which allows the syntesis of longer cDNAs (>7kb)