The endonuclease activity of FENs was initially identified as acting on a DNA duplex which has a single-stranded 5' overhang on one of the strands (termed a "5' flap", hence the name flap endonuclease).
The endonuclease activity of FENs was initially detected as acting on a DNA duplex featuring a single-stranded 5' overhang on one of the strands (termed a "5' flap", hence the name flap endonuclease).