DNA Modification

DNA Blunting

Blunting is the elimination of incompatible 3’ or 5’ overhangs for the promotion of blunt-end ligation.  Several approaches may be used for DNA end blunting. Terminal unpaired nucleotides may be removed from DNA ends by using an enzyme with exonuclease activity, which hydrolyzes a terminal phosphodiester bond, thereby removing the overhang one base at a time. DNA fragments with 5’ overhangs may be blunted by filling in a recessed 3’ terminus with DNA polymerase in the presence of dNTPs. End removal or fill-in can be accomplished using a number of enzymes, including DNA Polymerase I Large (Klenow) Fragment (NEB #M0210), T4 DNA Polymerase (NEB #M0203) or Mung Bean Nuclease (NEB #M0250). Once blunted, DNA is universally compatible with other blunt-ended fragments and vectors.  

  1. DNA Blunting Tutorial

    The first step in determining how your ends will be blunted is to determine if they are 5´ or 3´ overhangs. This tutorial will teach you how to identify what type of overhang you have, as well as which enzyme will blunt that end, and how.

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Protocols for DNA Blunting

Common Applications of Exonucleases and Endonucleases

NEB provides a list of common applications for our exonucleases and endonucleases.

Properties of Exonucleases and Endonucleases

NEB supplies many nucleases; several characteristics should be considered when choosing the one best suited to your particular research needs.