Answer:
DEAE cellulose columns are weak anion exchangers. This means that they contain a positively charged resin that binds to negatively charged proteins. Raising the pH above 8.5 will induce a negative charge on the resin.
Step-by-step explanation:
- Diethylaminoethyl cellulose (DEAE-C) resin carries the dimethylamino group (CH2-CH2-NH+-CH2-CH3) which is positively charged at neutral pH.
- This positively charged resin interacts with negatively charged protein samples.
- Being a weak anion exchanger, DEAE-C only remains partially protonated at most pH values.
- For effective anion exchange, the resin should be kept at 2 pH values below its PKa value.
- Since DEAE C columns possess a PKa of 8.5, raising the pH further will deprotonate the resin and induce a negative charge on it, it will, therefore, not bind to positively charged proteins.