How Much Alanine Is Present as the Completely Uncharged Species? At a pH equal to the isoelectric point of alanine, the net charge on alanine is zero. Two structures can be drawn that have a net charge of zero, but the predominant form of alanine at its pI is zwitterionic.
(a) Why is alanine predominantly zwitterionic rather than completely uncharged at its $\mathrm{pI} ?$
(b) What fraction of alanine is in the completely uncharged form at its pI? Justify your assumptions.