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Molecular Biology Tools

Products >  Molecular_Biology_Tools >  Modifying_Enzymes >  Nucleases >  Exonuclease_I

Exonuclease I

E. coli Exonuclease I is a 3' to 5' exonuclease that can be used specifically for single-stranded DNA degradation, resulting in the production of 5'-phosphate mononucleotides from the 3'-hydroxyl termini of single-stranded DNA. This 3' to 5' exonuclease is highly specific for single-stranded DNA and does not react with double-stranded DNA or RNA. Exonuclease I is inactivated by heat treatment at 80°C for 15 minutes.

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  • Single-stranded DNA degradation
  • Removal of ssDNA fragments in a reaction mixture
  • PCR primer digestion post-reaction 



Recombinant E. coli JM109 encoding E. coli Exonuclease I




Exonuclease I should not be used for DNA end blunting; short DNA ends are not an appropriate substrate for Exonuclease I. For DNA end blunting, use DNA Polymerase I, Klenow Fragment (2140A, 2140AK, 2140B, 2140BK) or Mung Bean Nuclease (2420A, 2420B) instead.

Unit Definition

One unit is defined as the amount of enzyme required to produce 10 nmol of acid-soluble product in 30 minutes at 37°C and pH 9.5 using heat-denaturated calf thymus DNA as the substrate.


5 U/µL


Supplied with 1 mL 10X Exonuclease I Buffer [670 mM Glycine-KOH, pH 9.5, 10 mM DTT, 67 mM MgCl2].

Cat. # Product Contents Size Price Units Select
2650A Exonuclease I 750 Units $66.00
2650B Exonuclease I 3,750 Units $257.00



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