Hello! I need to isolate pure low molecular weight DNA from salmon sperm DNA powder (Sigma-Aldrich, 31149). It says it has up to 5% of protein. How to dissolve and purify it properly?
Protease K digestion at 56℃ overnight followed by ethanol precipitation to recover DNA.
The preferable option is to dissolve the DNA in H2O or 10 mM Tris-HCl pH=7.0 containing 1% SDS and digest the solution with 10 mg/ml proteinase K during 30 min at 42ºC or even at 56ºC
. Afterwards you do a phenol extraction, followed by a phenol:chloroform:isoamylalcohol extraction and a precipitation with 0.3M Na-acetate and 2 volumes of 100% ETOH. After centrifugation and aspirating the supernatant, the pellet can be resuspended in H2O
This will give you DNA devoid of protein.
Best
Jose A.
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