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Definition of the isoelectric point of a protein

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What is the definition of the "isoelectric point" (pI) of a protein?

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Solution Summary

The solution contains an "official" definition of pI (isoelectric point), as well as an explanation of a more practical definition.

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The isoelectric point (pI) of a protein is the pH at which a zwitterionic molecule does not migrate in an electric field, because its NET CHARGE IS ZERO.

That's a definition that is easy to find but somewhat more difficult to understand. ...

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