Error Removal by T7 Enonuclease I

1. After PCR, purify PCR product using spin column, elute with 20 ul water

2. Add 15 units of T7 endonuclease I,  2 ul of 10 X T7 endonuclease I buffer.

3. Incubate at 37 oC for 1 hour to digest mismatch DNA