What will the isoelctric point (pI), if _pK₁=3.42 and _pK₂=11.54?

7.48

The correct answer is option 3. 7.48.

To calculate the isoelectric point (pI) of an amino acid with two pKa values, you can use the formula:

\(\text{pI} = \frac{\text{pKa1} + \text{pKa2}}{2} \)

Given:

\(pK_1 = 3.42\)

\(pK_2 = 11.54\)

\(\text{pI} = \frac{3.42 + 11.54}{2} = \frac{14.96}{2} = 7.48 \)

Therefore, the isoelectric point \((pI\)) is 7.48.

So, the correct answer is 7.48.