Blunting sticky ends

Sticky-ends can be blunted with appropriate enzymes

Following enzymatic activities are utilized for blunting of DNA ends.

  • 5'→3' polymerase activity to 'fill-in'.
  • Deletion by exonuclease activity.
  • Digestion by endonuclease.

Notice that the structure of the ends depends on the activities of enzyme.

DNA polymerase

Almost commercially available blunting kits contain the DNA polymerase. It fills-in 3'-sticky ends and deletes 5'-sticky ends. The blunting kits are useful because you don't have to prepare the reaction buffer containing dNTP.

S1 Nuclease

S1 Nuclease is one of endonuclease that recognize single-strand DNA or RNA. It can cut phosphodiester bondings where the site is not hybridized. Therefore, it can blunt DNA ends as well as remove loop structures on the dsDNA.

Images were created by ConstructMaster.

Enzymes of kits

VendorEnzyme in the blunting kit
TaKaRa BioT4 DNA Polymerase
Nippon geneT4 DNA Polymerase
TOYOBOKOD Polymerase

(on 2006.3.10)