18. Amino Acids and Proteins

Consider the amino acids histidine, phenylalanine, and serine in an enzyme. State which of these amino acids have R groups that would:

d. form salt bridges

What type of interaction would you expect between the R groups of the following amino acids in a tertiary structure?

c. serine and aspartate

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.

a. Where would you expect those amino acids to be located in the tertiary structure?

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.

b. Where would you expect the polar R groups to be in the tertiary structure?

When a protein folds into its tertiary structure, does the primary structure change? Explain.

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?

b. alanine and valine

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?

a. lysine and glutamate

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?

b. leucine and isoleucine

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?

d. glutamine and arginine

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.

a. Where would you expect these amino acid side chains to be located in the tertiary structure of the protein?

Myoglobin is a protein containing 153 amino acids. Approximately half of the amino acids in myoglobin have polar side chains.

b. Where would you expect the nonpolar side chains to be?

Would you expect to find this segment at the center or on the surface of a globular protein? Why?

Name the covalent bond that helps to stabilize the tertiary structure of a protein.

Collagen contains an amino acid that is a modified form of the naturally occurring amino acid.

a. Name the natural amino acid.