Before revision: Flap endonucleases (FENs, also known as 5' nucleases in older references) are a class of nucleolytic enzymes that act as both 5'-3' exonucleases and structure specific endonucleases on specialised DNA structures that occur during the biological processes of DNA replication, DNA repair and DNA recombination.
After revision: Flap endonucleases (FENs, also known as 5' nucleases in older references) are a class of nucleolytic enzymes that act as both 5'-3' exonucleases and structure-specific, endonucleases on specialised DNA structures that occur during the biological processes of DNA replication, DNA repair and DNA recombination.