concentrating the protein

D.K. dk at
Thu Jan 17 01:14:24 EST 2002

In article <20020117054023.21228.qmail at>, amirsamani at wrote:
>I have a cell line which express a truncated or of IGF-1 receptor.  This
>form of receptor is secreted out after expression.  To detect that I need
>to  concentrate the condtioned medium.
>1. What is the best way to concentrate proteins in medium?

Depends. If you can precipitate it (ammonium sulfate, PEG, etc)
it is probably easiest. Alternatively, stirring cell ultrafiltration. 
If volumes are too large, then binding to the column (hydroxylapatite,
others as appropriate for your protein) and eluting with 
steep step will do. 

>2. Is there a way to protect the protein from proteases during the

If it is serum-containing medium, there should be no problem with
proteases because sera contain enough protease inhibitors. If
it is serum-free medium, then there is not much one can do except
adding aprotinin/leupeptin. 


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