The primary sequence of the peptide listed below.
H2N -(1) - (2) - (3) - (4) - COOH
H2N - Asp-Thr-Phe-Lys-COOH
H2N – D -T – F – K – COOH
Use the one letter amino acid code and identify from N-terminusto C-terminus.
a.Determine the pI of the peptide. (Round to 2 decimalpoints)
b. Would mutating residue #3 to Ala change the pI of thepeptide? Explain.
c. Which type of noncovalent interaction would the indicatedresidue side chain make at the given pH? (H-bond, Hydrophobic orVan der Waals, or Ionic bond or Salt bridge)
Residue 1 @ pH 5.0
Residue 2 @ pH 6.0
Residue 3 @ pH 11.0
Residue 4 @ pH 10.0
d. Calculate the fraction of the peptides C-terminus protonatedat pH 2.5 (Round to 2 decimal points)
