Exonuclease III is a 3' to 5' exonuclease that removes mononucleotides from the 3'-hydroxyl termini of double-stranded DNA or DNA-RNA hybrids. Because a set number of mononucleotides are generated during each degradation, double-stranded DNA degradation is progressive. Exonuclease III will degrade double-stranded DNA containing a blunt end, a 5'-overhang, or a nick, but it will not degrade DNA with a 3'-overhang containing four or more bases. This 3' to 5' exonuclease can be inactivated by heating it at 65°C for 5 min. Exonuclease III is supplied in a buffer of 25 mM Tris-HCl (pH 8.0), 50 mM KCl, 0.5 mM DTT, and 50% glycerol.
- Preparation of single-stranded DNA for dideoxy sequencing
- Production of nested deletions in double-stranded DNA
- DNA-protein interaction analysis
- Site-directed mutagenesis
Recombinant E. coli
–20°C (–80°C when stored for more than 6 months)
Supplied with 10X Reaction Buffer [500 mM Tris-HCl (pH 8.0), 50 mM MgCl2, 100 mM DTT]
One unit is defined as the amount of enzyme required to produce 1 nmol of acid-soluble product in 30 min at 37°C and pH 8.0 using restriction-digested calf thymus DNA as the substrate.
Guo, L.H. & Wu, R.  Exonuclease III: Use for DNA sequence analysis and in specific deletions of nucleotides. Methods Enzymol. 100, 60–96 (1983).
Wu, C. An exonuclease protection assay reveals heat-shock element and TATA box DNA-binding proteins in crude nuclear extracts. Nature 317, 84–87 (1985).
Additional product information
Please see the product's Certificate of Analysis for information about storage conditions, product components, and technical specifications. Please see the Kit Components List to determine kit components. Certificates of Analysis and Kit Components Lists are located under the Documents tab.
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