NH4Ac-Miniprep becomes bad - why?

* * at alf1.ngate.uni-regensburg.de
Thu Aug 29 06:29:57 EST 1996


Hi there

Recently I switched from the Qiagen miniprep protocol to an
alternative method using an RNase containing resuspension buffer as
well, lysing with NaOH/SDS but precipitating genomic DNA and proteins
with 6M Ammoniumacetate. Precipitating the supernatant with Isoprop
gave a yield of plasmid (sequencable) as high as 25ug from a 1.5mL
culture. 
So I made a kit containing all the components that I need for the
prep. After a while (month) though my yields decreased rapidly until
the method didn't work at all anymore. So I made fresh solutions and
*bingo* it woked again. Now, after another month, the same problem
reoccures.
It would be much easier if I knew *what* solution is becoming bad and
I would be interested in *why* it happens and how to *avoid* it.
Anybody with similar problems???

Thanks
Mike




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