Proteins are commonly purified by ion exchange chromatography (IEC) as a final step. Which of the following statements is NOT true?

Select an option to attempt

1. A
   even proteins of similar isoelectric point can be conveniently separated by IEC, because interaction with the support is determined by the surface charge distribution of the protein rather than the net charge.
2. B
   in general, proteins can be eluted by increasing ionic strength
3. C
   above the isoelectric point, the proteins bind to anion exchangers.
4. D
   above the isoelectric point, the proteins bind to cation exchangers