What mode of column chromatography would be most useful for

What mode of column chromatography would be most useful for separating the following mixture of peptides?

Solution

Mode: Cation (“Ion”) exchange chromatography: This is because the stationary phase used in this chromatography is negaqtively charged functional group so that it can retain \"positively charged peptides\"

In case of peptide -1: FELAIGDMDLC (negatively charged peptide because net charge is -3. 0 at neutral pH) ---> this is because Phe-Glu-Leu-Ala-Ile-Gly-Asp-Met-Asp-Leu-Cys ---> elutes out of the colum becuase it is negatively charged and staionay phase also negatively charged

Isoelectric point: 2.9;

Net charge at pH 7.0:

-3.0

Average hydrophilicity:

-0.2

Ratio of hydrophilic residues /
total number of residues:

27 %

Peptide number-2: ERGEKRNKSKC --> Glu-Arg-Gly-Glu-Lys-Arg-Asn-Lys-Ser-Lys-Cys: (positively charged cations because net charge is +3. 0 at neutral pH) ---> this is because Phe-Glu-Leu-Ala-Ile-Gly-Asp-Met-Asp-Leu-Cys ---> retains on the colum becuase it is positively charged and stationary phase also negatively charged

Isoelectric point: 10.3

Net charge at pH 7.0:

3.0

Average hydrophilicity:

1.9

Ratio of hydrophilic residues /
total number of residues:

82 %

Hydrophobic interaction chromatography: Peptide 1 is considerably have higher hydrophobic nature

Net charge at pH 7.0:	-3.0
Average hydrophilicity:	-0.2
Ratio of hydrophilic residues / total number of residues:	27 %