Question

In: Biology

The tetrapeptide, NRMD, exhibits four pKa values: pK1 = 1.88, pK2 = 3.65, pK3 = 8.80,...

The tetrapeptide, NRMD, exhibits four pK_a values: pK₁ = 1.88, pK₂ = 3.65,
pK₃ = 8.80, and pK₄ = 12.48.

What is the isoelectric point for this peptide?

Group of answer choices

pI = 2.8

pI = 5.3

pI = 6.2

pI = 8.1

pI = 10.6

Expert Solution

Answer - 6.2

Explanation - The following net charge changes occur -

The isoelectric point (pI) is the pH where the net charge of the peptide is 0.

As can be seen from the diagram, that the net charge of peptide is between pK2 and pK3.

Thus, pI = (pK2 +pK3)/2

= (3.65 + 8.80)/2

=12.45/2

=6.225

Hence, isoelectric point for this peptide is 6.2.

gladiator answered 2 years ago

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