One method for separating polypeptides utilizes their different solubilities. The solubility of large polypeptides in water depends upon the relative polarity of their R groups, particularly the number of ionized groups. The more ionized groups there are, the more soluble the polypeptide. Which of each pair of the polypeptides that follow is more soluble at the indicated pH?

a. (Phe-Met)3 or (Glu)m at pH 7.0

b. (Lys-Ala)3 or(Gly)m at pH 7.0

c. (Ala-Ser-Gly)5 or (Asn-Ser-His)5 at pH 6.0

d. (Ala-Asp-Gly)5 or (Asn-Ser-His)5 at pH 3.0:

Polypeptides were essential amino acids although therefore realize that those acids become charged individually, provide various R groups but have specific isoelectric positions as well.

The polypeptides could be divided by analysis of multiple isoelectric points including fulfilling the following, even though a protein always at the isoelectric point seems to have the end up losing money.

At pH 7, it would be very negatively (-) charged, although (Phe-Met)₃ is even less positive and therefore less reversible.
This would be strongly positively (+) charge (equatorial) around pH 7, except for the amino as well as carboxyl-terminal, then (Gly)₂₀ which again is hourly rounding.
Although the carboxylate categories of Asp compounds become partly protonated although neutral throughout (Ala-Asp-Gly)₅, around pH 3, although the imidazole categories of His compounds become completely protonated although covalently bonded throughout (Asn-Ser-His)₅.
About pH 6.0, only certain polymers provide covalent bonds of polar Ser, however (Asn-Ser-His)₅ does have side bonds of polar Asn as well as partly protonated peptide bonds of His.