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Glycogen - DNA precipitation? - (Apr/21/2010 )

Hi, I need to ethanol precipitate my restriction digest, but there's only 40 ng of DNA in it so the pellet is invisible. I've been told that glycogen will co-precipitate and form a visible pellet. Anyone have a protocol on how much glycogen to add or any other useful info on this topic? Thanks!


Stupid question most likely, but why does the pellet need to be visible?

I always work with pellets that you cant see.


Mostly because it makes me feel better. Plus for some reason ethanol precipitation is always a problem for me. I can have a microgram of DNA when I start and lost almost all of it.


Also the glycogen acts as a "carrier", increasing the efficiency of the precipitation.


The only times I've used glycogen in a DNA precipitation I used:

1 μl glycogen (20μg/μl)
2.5 μl 3M sodium acetate
62.5 μl 100% Ethanol

added to a volume of 20 μl which was at about 50 ng/μl

Here's the protocol Sigma give though.