Exam 27: Amino Acids and Proteins

Bradykinin is a nonapeptide, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg. In addition to one mole of Arg, the following peptides are present after hydrolysis of bradykinin with chymotrypsin, Arg-Pro-Pro-Gly-Phe-Ser and Pro-Phe

Structure _____ (shown below) will remain at the origin in an electrophoresis experiment.

Which of the following dipeptides is L-Cys-L-Ala?

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is the product of an Edman degradation.

Which of the bonds in the following structure is cleaved by cyanogen bromide?

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is a peptide coupling reagent.

Consider the following octapeptide. Ala-Val-Trp-Lys-Phe-Gly-Arg-Met The fragments that would be obtained by a trypsin hydrolysis are Ala-Val-Trp-Lys and Phe-Gly-Arg and Met.

Edman degradation of the peptide saralasin shows that it has a sarcosine residue at the N-terminus. Sarcosine is Partial hydrolysis of saralasin with dilute hydrochloric acid gives the following fragments: What is the structure of saralasin?

In terms of the number of amino acid residues Cys-Ile-Ser-Asp-Gly-His-Gly-Gly would be classified as a(n) ________________.

The molecule shown below is an $\alpha$ -amino acid.

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is an amino acid in its zwitterionic form.

To what structural feature does the term "primary structure" refer?

Ninhydrin is used to determine the N-terminal amino acid of a peptide.

What are the R/S designations of the two stereocenters of isoleucine?

To what structural feature does the term "quaternary structure" refer?

Which of the following amino acids has an acidic side chain?

Which of the following tripeptides is not hydrolyzed by chymotrypsin?

How does phenyl isothiocyanate, Ph-N=C=S, react with a peptide in the Edman degradation?

What is the approximate value of the pK_a of the $\alpha$ -CO₂H of amino acids?

Provide the structure of Ser-Ala.