Exonuclease III (25,000u)

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

1. Weiss, B. (1976) J. Biol. Chem. 251, 1896–901.
2. Rogers, S.G. and Weiss, B. (1980) Meth. Enzymol. 65, 201–11.
3. Henikoff, S. (1984) Gene 28, 351–9.
4. Promega Product Information #9PIM181, Promega Corporation.