Recombinant protein precipitating upon freezing

Pow Joshi via methods%40net.bio.net (by pow.joshi from gmail.com)
Fri Feb 27 13:28:48 EST 2009


2009/2/27 <marguerite.b.colas from gsk.com>

> Hello Peter!
>
> I work at a pharmaceutical company and have been working on this study
> that involves freezing hemoglobin proteins, Every time we thaw our samples
> we notice that they go cloudy.
> At first we thought that we had been mixing our cell membrane pellet with
> the cell content supernatant. However, the time we took extra care to
> distinguish the supernatant from the pellet, we still noticed that our
> samples went cloudy after thawing them from the freezer. All our samples
> are kept in a -20c freezer.
>
> If you think you might know what might be happening to our samples, please
> let us know!



methinks, you could try adding extra salt to the supernatant; or check the
pH .... these are Fe bound proteins are'nt they?, perhaps if you need to
have near neutral pH? ... I wonder if the Fe is forming hydroxides and
precipitation out ...., in which case, you could add a bit of acid and
resolublize?  ....... Dima, may be you will be able to answer if I'm
completely off the track?

Pow

>
>
> thank you very much for your attention!
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