Sonication with PMSF/EGTA produces a precipitate.....why?

Eric Roush edroush at
Tue Nov 4 18:35:31 EST 1997

In article <01bce8a7$e01cfd70$373412ac at dough>, "Doug Hubatsch"
<Doug.Hubatsch at> wrote:

> Anybody else come across this?  When I sonicate bacteria in .1 mM PMSF/10
> mM EDTA, add 1% SDS and incubate for 30 min. at RT I get a DNA-like
> precipitate.  I don't think its because of the SDS, boiling the mixture
> doesn't put the precipitate back into solution.  The concentrations for
> PMSF and EDTA are well below other reported concentrations so I don't
> really have any idea what could be causing it.
> Any ideas?

Is there any reason to think that this precipitate is something
other than DNA?  It's been a while since I lysed bacteria, but
I remember the early steps of the process being quite gelatinous
in consistancy, not clearing up until after DNase treatment.

Eric Roush               When an eel
edroush at   bites your heel,
also coache at      makes you squeal,
                         pain you feel,
                         that's a moray.

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