The size of proteins may increase and not be possible to pass the membrane because of the protein coagulation at low pH. Low pH decreases the repulsion potential energy of the EDL which is resulting in the destabilization and aggregation of the protein particles.

How you membrane performs in different pH?

What type of membrane is used?

Regards

GB

Hi,

First, you need to be sure about MW of your scaffold protein remains the same and doesn't change with the pH of the media. Performing a simple SDS-PAGE or SEC-UV analysis can demonstrate whether there is an aggregation/coagulation as Byeongcheol Min pinpointed during pH differentiation.

What kind of ultrafiltration membrane material did you choose? Is there any pH-dependent possibility of the non-specific binding issue?

Is that a kind of purified protein and what else do you have in your sample solution (can your scaffold protein compose conjugations during pH adjustments?)

Yes, Byeongcheol Min in the acidic milieu, I also thought of aggregation, but my prtotein is during the whole filtration available as primary sturcture.

Could an agglomeration also exist during the primary structure?

And at the IEP I think that because the solubility due to the charges is to low.

But how are the charges at pH 7 that my protein passes through the membrane?

Thanks for the answer.

Grzegorz Boczkaj

It is a 200 cm ^ 2 membrane cassette with PES.

Because there is hardly any flow, increse the pressure.

Thanks for the answer.

Hey, İsmail Emir Akyildiz

The SEC analysis shows me that the protein is always the primary structure at different pH values, so the MW does not change. I use a PES, I think a cellulose membrane would be a way to avoid unspecific adsorptions. Some impurities are still in the sample solution, there is no conjugation.

Tessekürler.