FAQ: Can T4 DNA Polymerase be used to fill in 3' overhangs?

No, DNA polymerases cannot fill in 3' overhangs. To create blunt ends 3' overhangs must be removed. DNA Polymerase I, Large (Klenow) Fragment (NEB# M0210), T4 DNA Polymerase (NEB# M0203) or Mung Bean Nuclease (NEB# M0250) are the best choices to remove 3' overhangs.