Ammonium or Potassium Acetate?
Dr. Hiranya S. Roychowdhury
hroychow at nmsu.edu
Sat Feb 4 13:36:44 EST 2006
The both Amm-Ac and K-Ac does do the job fine. Ammonium is to be avoided if
you are using the DNA for ligation, since Ammonium ions seem to interfere with
The reason KOAc produces a big "precipitate" from the alk lysis buffers is the
fact that potassium salt of dodecylsulfate is insoluble in water. When you
add KOAc to ppt the NA, the Na-DS is converted to K-DS.
Quoting Wolfgang Schechinger <novalidaddress at nurfuerspam.de>:
> Dear JW
> Just checked sial.com for ammonium dodecyl sulfate. It's sold as a 30%
> aqueous solution. So it seems to be quite soluble and seems to me being
> not so much suited for the precipitation of proteins and geomic DNA.
> I also compared the precipitate formation of 3M KoAc vs 3M NH4OAc, bot
> pH 5,2 with HOAc with 0.1M NaOH / 1% SDS (the alkaline lysis solution).
> No ppt at all with the NH4OAc, KOAc made lotsa snow like a charm.
> Is there maybe a particular role of the Ammonium ions?
> PS please reply to the group, emails to this address will be delivered
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Hiranya S. Roychowdhury, Ph.D.
Dept. of Health and Public Services
Dona Ana Branch Community College
New Mexico State University
Las Cruces, NM 88003
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