Do all amino acids become zwitterions when dissolved in water?

Most amino acids become zwitterions when dissolved in water but not all do.  Whether or not an amino acid will become zwitterionic when dissolved in water depends entirely on the chemical structure of the amino acid. Only amino acids with a side chain that is capable of being charged will become zwitterions in water. Only 5 of the 20 amino acids have this innate ability including histidine, lysine, glutamic acid, aspartic acid, and arginine. Histidine is the most common example of an amino acid that becomes zwitterionic when dissolved in water.

Other amino acids only become zwitterions in water through bioconjugation and manipulation of the pH of the solvent. This is possible because the amino group and carboxyl group of all amino acids is ionizable.