At 1:50 PM -0400 6/24/08, R.M. Garavito wrote:
>Matthew,
>
>You're not going to ruin your column, but you won't get great
>performance either. Elution by pH change is a very common method,
>but getting a really linear pH gradient is very hard. The Mono Q
>matrix is a strong anion exchanger, meaning that it is insensitive
>to pH changes, i.e., you can't titrate it smoothly with acid or
>base. DEAE resins, which are weak anion exchangers, have a nice pH
>titration curve and lend themselves better to elution by pH change.
> This is the reason chromatofocusing is not a commonly used method,
>and its expensive.
There is a company the sells a proprietary buffer system and gradient
programming calculator to create a stable pH gradient for separation
on a MonoQ column or other strong ion exchanger.
<http://www.cryobiophysica.com/>
My problem with pH gradient techniques is that they don't work very
well unless your protein is happy in low ionic strength buffers,
which is almost never the case with my projects. This company now
claims that it can create the pH gradient with NaCl present, but I
haven't tried this yet.
- John
--
<http://xri.net/=john.newitt>
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