Exonuclease VII, (Exo VII) derived from E

coli, cleaves single-stranded DNA (ssDNA) from both 5′→3′ and 3′→5′ direction. This enzyme is not active on linear or circular dsDNA. It is useful for removal of single stranded oligonucleotide primers from a completed PCR reaction when different primers are required for subsequent PCR reactions. Digestion of ssDNA by Exonuclease VII is metal-independent.