Exonuclease III, also known as Exo III, it has 3′-5′ exodeoxyribonuclease activity, which digests one strand of double-stranded DNA (dsDNA) from a blunt end, 5′ overhang or nick, releasing 5′-mononucleotides and producing stretches of single-stranded DNA (ssDNA). Exo III is not active on 3′ overhangs of 4 or more bases in length, ssDNA, or on thioester-linked nucleotides. It also has 3′-phosphatase activity, RNase H activity, and apurinic/apyrimidinic-endonuclease activity.