Adventures in DNA extraction

[Robert Preston]

> 
> Now here's the funny part.  Through a series of blunders I discovered
> that substituting either sodium acetate  or sodium chloride for 
> the sodium citrate in the lysis buffer buggers up the protocol.
> I then get a massive precipitate upon ethanol precipitation, most of
> which will not dissolve in TE.  It also inhibits recovery of DNA from
> the pellet, although the quality is not reduced.  The stuff looks
> like glycogen, which of course like to co-partiion with DNA and
> precipitates with ethanol.  The presence of citrate, but not acetate
> or chloride, causes the glycogen (or whatever it is) to either
> partition into the interface or not precipitate with ethanol.  
> Can anyone explain this?
> 
> 
Joe (et. al.): a partial possible explanation hinges on the chelating
properties of citrate, the presence of which may alter the properties
of DNA-Metal, RNA-Metal, Glycogen-Metal, and Junk-Metal complexes in
a way that would give your results.  One test of that, if anyone cares,
would be to use acetate or chloride + EDTA in place of citrate.  But
if citrate works, who cares?

Rob
rapr at med.pitt.edu