appearance of "clean" DNA?

mwcrepeau at my-deja.com mwcrepeau at my-deja.com
Thu Jan 4 20:33:56 EST 2001


What does clean genomic DNA look like?  It should, of course, form a
clear, colorless solution when dissolved in TE buffer, but what about
viscosity?  I remember a graduate student looking at one of my first
plant DNA preparations when I was un undergrad and telling me that
there was a good yield because the prep was very viscous.

Later, someone else told me that DNA itself is not viscous in solution
and that any viscosity is due to contaminants.  That seems reasonable,
but it has also been my experience that the viscosity is almost
impossible to eliminate, even with several additional phenol/chloroform
extractions and/or ethanol precipitations.

What is responsible for the viscosity that is typical of plant genomic
DNA preps?  Moreover, if I could get my genomic DNA completely clean,
so that nothing was left but the nucleic acid itself, what would it
look like in solution?  And what would it look like as an ethanol
precipitate?  Would it appear as the white cloud that I am accustomed
to seeing, or is the white color due to bound protein and/or other
contaminants?

Perhaps this is just a theoretical question, since it may not be
possible to obtain completely clean genomic DNA, but I'm still curious
what people think about it.

Marc Crepeau
<mwcrepeau at hotmail.com>


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