L is naturally-occurring form for amino acids. Ionizable groups Zwitterion pKa for pKb for What form do we get at pH = 1? pH = 3.5? pH = 7.5? pH =9.5? and pH = 11.5? C OH O NH2 C OH O = 2.2 NH 2 = 9.5L is naturally-occurring form for amino acids. Ionizable groups Zwitterion pKa for pKb for What form do we get at pH = 1? pH = 3.5? pH = 7.5? pH =9.5? and pH = 11.5? C OH O NH2 C OH O = 2.2 NH 2 = 9.5