protein precipitation with TCA for dna extraction? - (Jul/24/2009 )

we've been exploring different options for protein precipitation during dna extraction. i understand that tca is commonly used for protein work and that any tca left over in the protein pellet is taken care of with acetone-- is it possible/feasible to purify nucleic acids from this supernatant? i'm not sure if tca plus the high-salt cell lysis buffer would work with an alcohol precipitation. sorry, my chemistry background is pretty weak! any insight would be appreciated. thanks in advance!

xoom on Jul 24 2009, 12:09 PM said:

Your first step is in understanding HOW each precipiation works biochemically. This involves an understanding of solvation effects. Proteins and nucleic acids will remain in solution because of the electrostatic interaction from charged atoms with hydrogen and hydroxide molecules that occur during the equilibration of water molecules: H2O -> (H+) + (OH-). High salt alone can precipitate a protein. Certain acids can precipitate a protein. Organic solvents can precipitate a protein. Nucleic acids can often be dropped out of solution by the same methods. Anything that breaks this interaction will cause precipitation.

Do some more diggin' into protein/nucleic acid solvation and you'll get your answers...