Peptide compose of 4 amino acids bonded together: glutamine, glycine, glutamic a

Question

Peptide compose of 4 amino acids bonded together: glutamine, glycine, glutamic acid, and the novel acid grensamine, which has an ionizable side group with a pKa of 5.9. At pH 7.0, this peptide has a net charge of -2. What is the charge on the protonated form of the grensamine side group? Peptide compose of 4 amino acids bonded together: glutamine, glycine, glutamic acid, and the novel acid grensamine, which has an ionizable side group with a pKa of 5.9. At pH 7.0, this peptide has a net charge of -2. What is the charge on the protonated form of the grensamine side group?

Explanation / Answer

Answer

N - Gln - Gly - Glu - Gre - C

Gln - pK1 = 2.17 pK2=9.13
Gly = pK1 = 2.34 pK2=9.60
Glu = pK1 = 2.19 pK2 = 9.67 pKr=4.25
Gre = pK1 = 2    pKr=5.9

NH3+ - Gln - Gly - Glu - Gre - COOH
                        COOH COOH

At pH 7

NH3+ - Gln - Gly - Glu - Gre - COO-
                          COO- COO-

Net charge +1-3 = -2

So, the protonated form of the grensamine side group is neutral charge

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.