An ion exchange column is used to separate several similar proteins. These proteins have the exact same sequence except on the N-terminus where they have the following sequences:
I. LAGPFVI
II. LADEFVI
III. LADECVI
IV. LAKRCVI
(a) Determine which type of ion exchange chromatography would work best and at which pH would you run this column.
(b) A gradient of increasing salt concentration is used for elution. Predict the order of elution for these fragments.