Exonuclease I, E. coli

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Last modified: 2008-07-15 14:57:15

Exonuclease I (Exo I) digests single-stranded DNA in a 3'→5' direction. Although it requires the presence of magnesium and a free 3'-hydroxyl terminus for activity, Exo I is active under a wide variety of buffer conditions and can be added directly into most reaction mixes. Exo I can be heat-inactivated by incubation at 80°C for 15 minutes.

Unit Definition:

One unit catalyses the release of 10nmoles of acid-soluble nucleotides from heat-denatured calf thymus DNA in 30 minutes at 37°C in 33 mM Tris-acetate, pH 7.8, 66mM potassium acetate, 10mM magnesium acetate, and 0.5mM DTT.

Storage Buffer:

50% glycerol containing 50mM Tris-HCl, pH 7.5, 0.1 M NaCl, 0.1mM EDTA, 1mM DTT, and 0.1% Triton® X-100.

Quality Control:

Exonuclease I is tested in degradation of single-stranded DNA and is free of detectable RNase, endonuclease, and double-stranded exonuclease activities.

Last modified: 2008-05-14 16:46:46

Applications

• Removal of residual primers from amplification reaction mixes
• Removal of single-stranded DNA from nucleic acid mixtures

Figure 1. Specificity of Exonuclease I for ssDNA. 200 ng of EcoR I-linearized pUC19 dsDNA and 1µg of a 100-mer ssDNA oligo were mixed in 1X TA Buffer and incubated at 37°C for 20 min in the absence or presence of 10 units of Exonuclease I. As seen on this 1% agarose gel, Exonuclease I completely digested the linear ssDNA oligo, but left the linearized plasmid dsDNA intact. Lane 1, size markers; Lane 2, minus Exo I; Lane 3, plus Exo I.

Last modified: 2008-05-14 16:46:46

Protocols for: Exonuclease I, E. coli

(catalogue number X40501K / X40505K / X40520K)

Please note: all protocols off site are the responsibility of the products supplier

Last modified: 2008-05-14 16:46:46