Midi-preps

Bernard Heymann bheymann at bragg.bio.purdue.edu
Wed Sep 22 10:21:39 EST 1993


In article <1993Sep21.151134.160 at ntet.nctr.fda.gov>,
wmelchior at ntet.nctr.fda.gov (Bill Melchior) wrote:
> Plasmid protocols frequently call for making this fresh (eg, Maniatis et
> al).  I, on the other hand, haven't seen any problems with a solution well
> over a year old (stored in a polythylene bottle as suggested by Kieser in
> Plasmid 12:19-36, 1984, who does NOT suggest making it fresh).  Birnboim,
> Meth. Enz. 100:243-255, 1983, says, "The shelf life at room temperature is
> about a week or longer, depending upon the source of SDS; ...."  I'd like
> to know if nishir or anyone else has actually had bad experiences with old
> alkaline SDS, or is it just folklore?  What happens when the solution goes 
> bad?
> 
> Comments welcomed; Bill
> 

The one place where I had frustrating problems associated with old
alkaline SDS or alkaline SDS made from a high concentration stock
solution (10x), was in sequencing. The gels showed the generation
of random length fragments regardless of the dideoxy nucleotide used.
Simple cut and paste of plasmids did not seem to be affected by degraded
alkaline SDS solution used in their preparation.

Bernard Heymann



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