| [Visitor (112.0.*.*)]answers [Chinese ] | Time :2023-05-10 |  pI Definition:
2. pH value when the net charge of amino acids is zero.
3. Amino acids are amphoteric electrolytes, showing negative charge in alkaline solution, positive charge in acidic solution, and pH when the positive charge and negative charge of amino acids are equal in a certain pH solution, which is called the isoelectric point of the amino acid.
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The formula for calculating pI:
1. For neutral amino acids with non-dissociable side chain R groups, pI=1/2 (pKa1 PKa2).
2. For amino acids with multiple dissociation groups, as long as you write out its dissociation formula, and then take the average value of pKa on both sides of the isoelectric fastitutic ion to obtain its pI value.
Note: The pI value is basically independent of the ion concentration, but only depends on the pK value on both sides of the isoelectric neutral ion A. |
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