Midi-preps

[Jorge Blackhall]

Bill Melchior  wrotte: 
> 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

Hi!
Our experience with old alkaline SDS sais that is not just folklore.
We have had probrems in sequencing those DNA preparations purified with old
NaOH-SDS (solution II). 
It is true that there is not problem to digest that DNA with endonucleases,
in our hands at least.

Comments welcomed,
Jorge Blackhall 
<proj at bio.embnet.se>