Problem with protein concentration - (Jan/08/2004 )
I would not try to concentrate the sample using centricon, i would lyophilize it first and then do buffer exchange on a g-25 column using ammonium bicarbonate buffer and another lyophilzation, which will give me only protein no contamination of any salt, the recovery will be around 80-90%
If the protein is pure when you start the centricon but dilute, we recommend a simpler method. Works when you need the target in a precise final buffer. Do a preparative acrylamide gel, load enough of your protein. Observe under UV, and cut out the grey target band. Macerate with a sealed capillary tube and soak in target buffer overnight at 37C. Dialyze against target buffer to remove stray acrylamide and voila! Repeat, combine, Repeat, combine.
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