[sci.bio] More on DNA Purification

whycare@athena.mit.edu (nemo) (06/30/90)

Having received several e-mail responses to my last posting on DNA
Purification,
I came up with some more questions of interest: 

1) Why does protein and not DNA partition out into the
phenol/chloroform/(isoamyl    alcohol) phase in the organic solvent
extraction? 

2) What phases would I see in a test tube if I took a DNA/some unwanted
protein      sample suspended in 70% ethanol high salt concentration,
added an equal volume    of phenol/chloroform/isoamyl alcohol (24:24:1),
mixed and then centrifuged the    entire mixture? Here's my guess:

   TOP OF TUBE
 
   organic phase (phenol/chloroform/alcohol)
   white interface  (protein)
   aqueous phase  (water)
   DNA pellet
   
   BOTTOM OF TUBE

   Then to get the purified DNA, I'd remove the organic phase and white
interface
   and vacuum-dry the pellet.

   Is the above procedure orthodox?
   If not, what is orthodox?
   What would I really see if I'm wrong about my guess?

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