Question

For each scenario determine which type of column chromatography would be the best choice to separate these proteins. For each which proteins would elute off of the column first? Please explain your answers. a) Protein A: LLLGGAAPPVLHKWMMAPG or Protein B: HHKGLARTIRKHLLIMGASHK b) Protein A: LLLGGAAPPVLHK WMMAPG or Protein B: VVLTCNMI

Answer 1

Answer:

The correct answers are:

a) "cation exchange chromatography, Protein A will elute first"

b) "size exclusion chromatography, Protein A will elute first".

Explanation:

Liquid chromatography is a common method for separation of proteins, which is based on the differences of affinity that the proteins have to a column. For the separation of the two first proteins the best choice will be to use a cation exchange chromatography, a method that uses a column that is negatively charged. Protein A will be the first to elute because Protein B has more affinity to the column because it is highly positive charged at neutral pH due to its high content of histidine and lysine residues. Regarding the separation of the second group of proteins, the best choice will be to use a size exclusion chromatography. In this technique the proteins are separated based on its molecular size, and the first one to elute will be the one that has a bigger size, which is Protein A.