appearance of "clean" DNA?

[Rosie Redfield]

Because the long DNA filaments in a chromosomal DNA prep aggregate 
into a cloud of fibers when ethanol is added, there's an easy way to 
quickly get rid of most contaminants.

Don't collect the DNA by centrifugation, as the pellet will contain 
all contaminants that are also insoluble in ethanol.  Instead collect 
the DNA the traditional way, by 'spooling' it onto a glass pipette as 
it comes out of solution, or by simply swirling the ethanol mixture 
until the precipitating DNA fibers form a non-viscous clump and then 
fishing the clump out with a pasteur pipette or clean forceps.

This method only works for chromosomal DNA, because plasmids and RNA 
won't clump.

Rosie Redfield


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