How is RNA isolated from DNA in AGPC RNA...

[burnholywater]

...isolation? I understand the protein degredation and seperation, but RNA and DNA have very similar properties. So what reagent in AGPC precipitates DNA and not RNA and how?

[raerae_2001]

apparently the two are separated at the centrifugation step with RNA being in the aqueous phase and DNA being at the interphase of the aqueous and phenol-chloroform layers

Original Article describing procedure:

Analytical Biochemistry
Volume 162, Issue 1 , April 1987, Pages 156-159

[plantgirl]

It's the acidic phenol that separates the DNA from the RNA. When you add AGPC, or just acidic phenol (pH < 6), to your aqueous solution (containing your nucleic acids) the DNA will move into the interphase or organic phase along with the proteins. The RNA is left in the aqueous phase. If you use a more basic phenol (like pH 8) the DNA will stay in the aqueous phase - this is used for DNA extractions or simultaneous DNA/RNA extractions.