Question

Isoelectric point and molecular weight of proteins given ion exchange chromatography

Answer 1

Ion exchange protein purification is possible because most proteins bear nonzero net electrostatic charges at all pHs except at pH=pI (isoelectric point). At a pH >pI of a given protein, that protein becomes negatively charged (an anion), at the pH<pI of that same protein, it becomes positively charged (a cation).