an amphoteric electrolyte

An amphoteric molecule or substance, such as amino acid or protein. Ampholytes can ionize to form either cations (acids) or anions (bases) because they have both acidic (proton donor) and basic (proton acceptor) groups. The sum of charges carried by these groups determines the net charge of the molecule. There is a pH called the isoelectric point (pl), at which the sums of negative and positive charges are equal and the molecule has zero net charge.