Why does ion exchange chromatography depend on the pH of the medium?
A)The charge of each amino acid R group depends on the medium's pH.
B)The charge of each nucleic acid R group depends on the medium's pH.
C)The charge of each fatty acid R group depends on the medium's pH.
D)The charge of each terminal amino acid depends on the medium's pH.
E)The shape of each protein depends on the medium's pH.

Question

Quizplus · Accepted Answer

Ion exchange chromatography separates molecules based on their net surface charge. The charged groups on the molecules interact with oppositely charged ions immobilized on the column matrix. The net charge on each molecule is determined by the pH of the surrounding medium because the charge of ionizable groups such as amino (NH3+) and carboxylate (COO-) groups on amino acids, or the phosphate groups on nucleic acids, is pH-dependent. Therefore, the pH of the medium will control the charge of the molecules and thus their interactions with the column matrix.

Why Does Ion Exchange Chromatography Depend on the PH of the Medium