Phenol Extraction

Dom Spinella dspinella at
Wed May 7 09:46:44 EST 1997

Patrick writes:

> Why do we use acid phenol for RNA extraction and basic phenol for DNA 
> extraction??
> Thanks for the answer.

At acidic pH, DNA is selectively retained in the organic phase and the
interphase, leaving RNA in the aqueous phase and affording a measure of
purification from DNA.  Also, the acidic pH reduces the activity of many
nucleases.  Hence, low pH for RNA extractions.  At basic pH, both DNA
and RNA partition into the aqueous phase. However, for DNA extractions,
you need to avoid acid-induced depurination; thus, high pH for DNA
extraction. Hope that answers your question.  -- D.G. Spinella

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