protein aggregation - aggregation during concentration (Jun/29/2004 )

hi,
I have problems with aggregation of my proteins during concentration using PEG 8000. So, up to a specific concentration of about 0,5 mg/ml the refolded protein is aggregating during concentration. But I need a concentration of about 1 mg/ml for cristallisation.
Thanks for helping,
Paemi

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There is another topic discussing ways to concetrate protein

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I do not know how your protein is behaving in the high salt, but one of my favorite method is the Ammonium Sulfate Precipitation, at %58 salt, all of the proteins are supposed to precipitate. Additionally, you can load your sample onto ion-exhange column, and elute this with salt gradient. Sometimes I have 2 or 3 liter solution to concentrate and I load all into column and elute and get the volume to 20 ml in half-day. Then take it into centriprep.
Good luck, structural biologist allways have this concentration problem.
Mehmet

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