Urea and ion exchange

.Krimer Alejandro a.krimer at biosidus.com.ar
Wed Jun 30 08:06:59 EST 1999

	Dear Netters:

	I disagree with Roney, may be some protein could bind to ion
exchange resins; but the general rule is not binding.
	I have heard some explanations a few years ago about the question. I
think Urea exposes hydrophobic sites in the protein reducing the interaction
with a charged matrix.
	In my experience working with more than 10 different proteins urea
concentracion should not exceed 2-3 M.
	Hope this helps.

	Alejandro Krimer
	R & D Department
	Bio Sidus

> In article <B0001705182 at spider.cigb.edu.cu>, ricardo.silva at cigb.edu.cu
> wrote:
> > Hi all,
> > Several colleagues of mine have advised me against using high 
> > concentrations (8 M) of urea in ion exchange runs. In their 
> > experience, nothing binds under this conditions. This puzzles me, 
> > because being urea an uncharged species, it shouldn't interfere with 
> > ion exchange, right?
> > Does anybody have similar experiences and/or have an explanation?
>    All I can say is that I have seen it done a few years ago, and it
> worked - I believe it was on Q-Sepharose and eluted with KCl. One source
> of trouble I can think of is to get your eluting salt to dissolve in hi
> conc urea. Just 2 cents on this one...
> roney

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