Zwitterion

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An amino acid, in its (1) nominal (unionized) and (2) usual, zwitterionic forms.
An amino acid, in its (1) nominal (unionized) and (2) usual, zwitterionic forms.

A zwitterion (first part pronounced "tsvitter", from German "Zwitter" — "hybrid," "hermaphrodite") is a chemical compound that is electrically neutral but carries formal positive and negative charges on different atoms.[1] Zwitterions are polar and usually have a high solubility in water and a poor solubility in most organic solvents.

Ampholytes are molecules that contain both acidic and basic groups (and are therefore amphoteric) and will exist mostly as zwitterions in a certain range of pH. The pH at which the average charge is zero is known as the molecule's isoelectric point.

[edit] Applications

Ampholytes are used to establish a stable pH gradient for use in isoelectric focusing.

Typical examples of zwitterions are:

Less common examples of zwitterions are:

[edit] References

  1. ^ Compendium of Chemical Terminology, zwitterion