Exonuclease III is a 3´→5´ exonuclease specific for double-stranded DNA. The enzyme catalyzes the stepwise removal of mononucleotides starting from a 3´-OH at nicks, blunt ends, recessed ends and 3´-overhangs of less than 4 bases, yielding nucleoside 5´-phosphates. Exonuclease III will also degrade DNA from 3´-phosphate ends due to its intrinsic 3´-phosphatase activity. In addition, the enzyme has apurinic endonuclease activity and ribonuclease H activity. Exonuclease III is used in conjunction with S1 nuclease for unidirectional deletion of sequences from the termini of DNA fragments.
Features - Benefits
Flexible:Control deletion rate by varying incubation temperature.
May Be Heat-Inactivated:Exonuclease III may be inactivated by heating to 75°C for 10 minutes.
Provided with 10X Reaction Buffer:660mM Tris-HCl (pH 8.0 at 25°C), 6.6mM MgCl2.
Applications
Generating nested sets of deletions with double-stranded, linear DNA.
Preparation of single-stranded DNA.
References
Weiss, B. (1976)J. Biol. Chem.251, 1896–901.
Rogers, S.G. and Weiss, B. (1980)Meth. Enzymol.65, 201–11.