1) At which pH will a solution of isoleucine be fully in it's zwitterion species, 100% = [HAA]

pKa1 = 2.36

pKa2 = 9.68

pI = 6.02

2) At which pH will a solution of proline have equal concentrations of its fully protonated species and zwitterion species, [H₂AA⁺] = [HAA

pKa1 = 1.99

pKa2 = 10.96

pI = 6.48

Fully Protonated Zwitterion Fully Deprotonated (H2AA) (HAA) (AA) pKa1 =pKa2 Fully Protonated Zwitterion Fully Deprotonated (H2AA) (HAA) (AA) pKa1 pKa2