Hi Mahfuza..

Is there any specific reason for storing it at 4 degree? if the purpose is just storage then why don't you store it at -20degree O/N.

As long as you don´t have nucleases in the tube it doesn´t matter whether you store the samples o/n at 4°C or at -20°C. I often run a digest in the late afternoon and left the samples in the cycler at 4°C until the next day.

Hi Mahfuza,

As Gaurav mentioned above, you should store it at -20 degrees. The chance of further digestion by restriction enzymes (in case you have not inactivated them) and attack by nucleases (if any present) is negligible at -20, so its better than 4 degree storage