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 polypeptide, (gly)20 or (lys−ala)3 , is more soluble at ph 7.0 ? (gly)20 (lys−ala)3 which polypeptide, (glu)20 or (phe−met)3 , is more soluble at ph 7.0 ? (phe−met)3 (glu)20 which polypeptide, (ala−asp−gly)5 or (asn−ser−his)5 , is more soluble at ph 3.0 ? (asn−ser−his)5 (ala−asp−gly)5 which polypeptide, (ala−ser−gly)5 or (asn−ser−his)5 , is more soluble at ph 6.0 ? (ala−ser−gly)5 (asn−ser−his)5