1. Digest DNA with desired RE so that total volume is 40 µl.
2. Add following to the reaction:
5 µl 10X T4 pol buffer
1 µl each dNTP's
1 µl T4 pol
Total volume of the rection is 50 µl
3. Incubate 30 min @ RT.
4. Heat inactivate @ 75C for 15 min
5. Ethanol precipitate (1/10 vol of 5M NaCl & 3 vol EtOH)
6. Wash with 70% EtOH & spin again.
7. Resuspend in H₂0. Ready to use.

* Optionally use phenol extraction after step 4