Protein concentration with PEG

AllisonH via methods%40net.bio.net (by nospam from gmail.com)
Tue May 1 10:13:32 EST 2012


How about Ficoll?  The powder can be used just like PEG.

Allison



On 30/04/2012 7:50 AM, WS wrote:
> Dear Experts,
>
> You are probably aware of the protein concentration method by
> "dialyzing" against polyethyleneglycol. My question is regarding the
> MW of PEG and the pore size of the tubing: Currently, I am using
> PEG20000 (avg MW 15k-20k) and a dialysis tubing with a cutoff of 14kD
> for globular proteins. In my experience, this is working very well
> (and cheap), esp. for large volumes.
>
> We just got some concerns now that some of the PEG could make it
> across the membrane. Is there any need to be concerned? Which would
> mean to switch to PEG35k or higher and/or tubing with a lower cut/off,
> both increasing the expenses. As I understand PEG, the molecules will
> get quite huge due to hydratation and PEG always has some low MW size
> "contaminants" i.e. molecules shorter than desired.
>
> Anything you can suggest?
>
> Thanks!
>
> Wo



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