DNA Polymerase I (E. coli) is a non-thermostable DNA polymerase with inherent 3´→ 5´ (proofreading) and 5´→ 3´ exonuclease activities, in addition to a lower and non-specific ribonuclease H activity. The 5´→ 3´ exonuclease activity removes nucleotides ahead of the growing DNA chain, allowing nick-translation. Thus, DNA Polymerase I (E. coli) displays no strand-displacement activity and may be used for DNA labelling by nick-translation, in conjunction with DNase I, or second-strand cDNA synthesis, in conjunction with RNase H. DNA Polymerase I (E. coli) accepts modified nucleotides (e.g. biotin-, digoxigenin-, fluorescent-labelled nucleotides) as substrates for the DNA synthesis.
Applications:
– DNA labelling by nick-translation
– Second-strand synthesis of cDNA