Exam 24: Amino Acids, Peptides, and Proteins

Provide a structure of the dipeptide Ile-Gln.

Could L-proline be made using reductive amination? If so, show the starting material. If not, explain why.

Show how a monosaccharide such as glucose can attach to a protein structure through the formation of an O-linked glycosidic bond with Ser. (Hint: This structure would be properly called an acetal.)

Peptide bonds are ________.

Describe how electrophoresis works.

Nearly all naturally occurring amino acids ________.

Which of the following amino acids does not contain an aromatic R-group?

Before Edman degradation, Fredrick Sanger developed the first method to analyze the N-terminal amino acid of a protein using 2,4-dinitrofluorobenzene in the following reaction. Propose a mechanism for this reaction.

Which of the following amino acids has its α-carbon as part of a 5-membered ring?

The term ________ is sometimes used to describe peptides which contain four to ten amino acid residues.

Which of the following amino acids has its isoelectric point at the lowest pH?

In an electrophoresis carried out at pH 9.0, does phenylalanine migrate toward the cathode, migrate toward the anode, or not migrate at all? Explain briefly.

Provide the structure of L-valine at pH 12.0.

Suggest a method for resolving a racemic acid.

What peptide remains after two sequential Edman degradations of the pentapeptide

Draw the form of L-tryptophan which is present at biological pH, pH = 7.4.

What compound is also known as Sanger reagent, and how is it used in peptide structure determination?

Provide the structure of Thr-Gln-Met.

Provide a structure of the tripeptide VKE.

Provide a synthesis of racemic valine from 3-methylbutanoic acid.