DNA precipitation- Why EtOH? - Why we use EtOH and NaOAc together? (Aug/12/2010 )

Hi,

When we precipitate DNA, we use NaOAc(Sodium acetate, salt) and EtOH(ethanol).

I know Na+ can neutralize - charge of phosphate of DNA, making DNA less hydrophilic.
So DNA can be precipitated out of water.

But I am not sure why we use EtOH.
Can you explain that?


Thanks,

You don't have to use EtOH, you can use isopropanol (2-propanol, propan-2-ol). Basically the DNA is less soluble in alcohols than it is in water, especially in the presence of salt.