If you wanted to use cation exchange chromatography to purif

If you wanted to use cation exchange chromatography to purify a protein, what should the pI of the protein be? (~7, Less than 7 or more than 7). Explain how and why cation exchange would be used to purify this protein.

Solution

For an cation exchange the protein should be positively charged hence the pI must be less than 7. Under such condition the resin bed being negatively charged and the protein under pI is positively charged are attracted and effective column separation occurs.