3 replies to this topic

[Ikar]

Hi!
What is the difference in using whether potassium or sodium acetate for a DNA preparation when I am
doing the alcohol precipitation?

br,
Ikar

[phage434]

Probably none.  The place where it matters is in neutralization of SDS lysis buffer, where the potassium salt is used to precipitate potassium dodecyl sulfate, which helps to bring down the genomic DNA, leaving plasmid DNA in solution.

[Ikar]

phage434, on 02 January 2011 - 02:22 PM, said:

Probably none.  The place where it matters is in neutralization of SDS lysis buffer, where the potassium salt is used to precipitate potassium dodecyl sulfate, which helps to bring down the genomic DNA, leaving plasmid DNA in solution.

Did I understand correctly?
-> If I am doing a plasmid isolation the sodium acetate is used to neutralize the SDS lysis buffer

-> If I am doing a isolation of genomic DNA I use potassium acetate to precipitate potassium dodecyl sulfate (or did you mean sodium dodecyl sulfate?)

[phage434]

No, the other way around.  Potassium acetate is used to precipitate the SDS during a miniprep, forming insoluble KDS.  Either could be used (though the sodium salt is traditional) in a normal ethanol precipitation.