Recombinant protein precipitating upon freezing

[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!

thank you very much for your attention!
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