FAQ: Can Thermolabile Exonuclease I be used to blunt dsDNA?

No. Short ssDNA ends are not a substrate. Use DNA Polymerase I, Large Klenow Fragment (NEB# M0210) to fill in 5′ overhangs and chew back 3′ overhangs, or use Mung Bean Nuclease (NEB# M0250) to chew back 3′ or 5′ overhangs. Note: 3′ overhangs cannot be filled in.