What is a zwitter ion?

A zwitter ion is an inner salt of amphoteric compound resulting due to the reaction between acidic and basic groups. Amino acids and proteins constitute both acidic (-COOH ) and alkaline (-NH2) groups, as a result they can form salts with acid and alkali. When dissolved in either acid or alkali, they behave like anions and cations, migrating to either cathod or anode. However, at a definite pH, called isoelectric pH, they form inner salt or zwitter ions, at which they are least soluble and electrically neutral.