EN01, Exonuclease I (Exo I) This product is derived from recombinant E.coli strain, carrying the Exo I gene, with exonuclease activity of hydrolyzing single-stranded DNA from the 3'-5' direction, which can gradually release deoxyribonucleic acid 5 'monophosphate and leave a complete 5' end dinucleotide.