Exam 19: Biomolecules: Amino Acids, Peptides, and Proteins

Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. -Refer to instructions. Leucine is described as an essential amino acid. What does this mean?

Which amino acid results from the following sequence of transformations?

Consider the following structure. Based on this structure answer the following question(s). -Refer to instructions. Circle the peptide bonds.

Match a structure from the list below to each of the following terms. -The product of an Edman degradation.

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

Match a structure from the list below to each of the following terms. -A peptide coupling reagent.

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

Which of the following amino acids is a secondary amine?

Consider the following structure. Based on this structure answer the following question(s). -Refer to instructions. Identify the C-terminal amino acid and the N-terminal amino acid.

Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. -Refer to instructions. How many possible stereoisomers of leucine are there?

Which of the following amino acids migrates to the positive electrode on paper electrophoresis at a pH of 7.0?

Consider the following structure. Based on this structure answer the following question(s). -Write the equation for the reaction, using methanol (CH₃OH), that would render the carboxyl group of alanine unreactive.

Match a structure from the list below to each of the following terms. -Source from which many coenzymes are derived.

Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. -Refer to instructions. Draw the structure of the predominant form of leucine at pH = 1.50.

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

Which of the following amino acids contains two stereocenters?

Refer to the data below to answer the following question(s). Porcine dynorphin is a neuropeptide having 17 amino acid residues. Its structure is shown below. Tyr−Gly−Gly−Phe−Leu−Arg−Arg−Ile−Arg−Pro−Lys−Leu−Lys−Trp−Asp−Asn−Gln -Refer to instructions. What fragments would result if dynorphin were cleaved by trypsin?

Match a structure from the list below to each of the following terms. -An amino acid in its zwitterionic form.

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

Which of the following amino acids migrates to the negative electrode on paper electrophoresis at a pH of 7.0?