Isoelectric Point

Question

Isoelectric point (pI) of amino acid is pH at which:

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1. **Definition**: The isoelectric point ($pI$) is the specific pH at which a molecule carries **no net electrical charge**.
2. **State**: At this pH, the molecule exists almost entirely as a dipolar **zwitterion** ($^+H_3N-CHR-COO^-$).
3. **Properties at pI**:
   - It does not migrate in an electric field (electrophoresis).
   - Solubility is usually at its **minimum** because the molecule has no net charge to interact strongly with water.
4. **Calculation**: For neutral amino acids, $pI = (pKa_1 + pKa_2) / 2$.

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Isoelectric Point

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More isoelectric point Practice Questions

At isoelectric point, an amino acid exists as:

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