TCA precipitation

Peter Pediaditakis pxpst2 at vms.cis.pitt.edu
Fri Jan 30 09:55:04 EST 1998

In article <01bd2cfc$c93f6e00$0e3163c3 at f.--j.beal>, "Jane Beal"
<J.D.Beal at btinternet.com> wrote:

> Hi All
> Does anybody know how small, in terms of M.W or AA residues, a peptide has
> to be before it is soluble in TCA or sulphosalycilic acid.  Does solubility
> in these reagents depend on the source of protein.

A lose approximation would be 20 KD.  But the bigest problem with TCA is
that proteins of similar molecular mass may precipitate differently in
TCA.  Thus if you had a mixture of proteins some will come down while
others do not.  Factors influencing TCA precipitation include
Glycosylation(reduces efficiency), Hydrophobicity and others.
I think that the Wessel Fluege method is better and the Phenol Ether
method is better

reference:  Concentration of Dilute Protein for Gel Electrophoresis, Anal.
Biochem., 226, 382-383 (1995)

Also TCA stored for a while can breakdown and form HCl which can hydrolyze
your protein

Peter Pediaditakis

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