Ion exchange

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Mar 14, 2017

DEAE cellulose is positively charged at neutral pH and therefore binds negative charged proteins.

where is Ion exchange here taking place. (can anyone pls direct me to a picture where resin functional group interacts with a protein)

If a Ca+ ions replaces Na+ mobile ion that is bound to the moiety of the resin it makes sense there is an exchange of strong affinity vs weak affinity ion.

I don't understand when this come to proteins especially with Q column

Quaternary ammonium binds to negative charge protein, can maintain their charge density over a pH range of 0–14. So where does ion exchange takes place?


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relaxin 11 months ago

The diethylaminoethanol group of DEAE cellulose is weakly positively charged, so negatively charged proteins will bind to it. Increasing NaCl concentration will elute the proteins out of the resin according to the strength of their binding, because the Cl- ions will compete with the negatively charged proteins and displace them. So the ion exchange involves the exchange of Cl- ions with the negatively charged proteins (which are acting as negative ions).

The Q column is a stronger positively charged resin, but the principle is the same.