Organic Chemistry III

Professor Carl C. Wamser

Chem 336 - Spring 2007

Chapter 27 Homework Answers

Carey, pages 1200 - 1203 :

Problems 27.25 - 39


1. Write the structure of the tripeptide alanylprolyllysine, as it would appear at pH 7.

After acid hydrolysis into individual amino acids, show the products as they would appear at pH 1.

2. Show how you might start with a dipeptide, isoleucylglutamine, and specifically add a methionine to the N-terminus.

Repeat for the C-terminus.

3. An unknown hexapeptide is determined by complete hydrolysis to have the amino acid composition Ala (2), Lys, Glu, Phe, Cys.

Edman degradation releases Ala followed by Cys.
Chymotrypsin hydrolysis gives two tripeptides, both of which have Ala at their N-termini.
Trypsin hydrolysis gives a pentapeptide plus Glu.
Identify the amino acid sequence of the hexapeptide.

Ala-Cys-Phe-Ala-Lys-Glu