including modified dna and rna dna rna hybrids as well as other hybridising nucleic acid like molecules e g peptide nucleic acid pna the term u201c polynucleotide processive enzyme u201d as used herein is to be interpreted broadly and relates to any enzyme that interacts with a polynucleotide and moves continuously along the polynucleotide the enzyme is preferably a polymerase enzyme and may be of any known type for example the polymerase may be any dna dependent dna polymerase if the target polynucleotide is a rna molecule then the polymerase may be a rna dependent dna polymerase i e reverse transcriptase or a rna dependent rna polymerase i e rna replicase in a preferred embodiment of the invention the polymerase is t4 polymerase in further preferred embodiments of the invention the polymerase is either e coli polymerase iii holoenzyme mchenry ann rev biochem 1988 57 519 t7 polymerase schwager et al methods in molecular and cellular biology 1989 90 1 4 155 159 or bacteriophage t7 gene 5 polymerase complexed with e coli thioredoxin tabor et al j biol chem 1987 262 1612 1623 each of these polymerase enzymes binds to a target polynucleotide with high processivity and fidelity and therefore maintains a polymerase polynucleotide.