Q11. Which amino acid is most likely to be found in the center of a tightly packed, water-soluble globular protein such as myoglobin?

Background

Topic: Protein Structure and Amino Acid Properties

This question tests your understanding of how amino acid side chains influence their location within a protein, particularly in water-soluble globular proteins. The hydrophobic effect drives certain amino acids to be buried in the protein core, away from water.

Key Terms and Concepts:

• Hydrophobic amino acids: These have nonpolar side chains and tend to be found in the interior of proteins to avoid contact with water.

• Hydrophilic amino acids: These have polar or charged side chains and are often found on the protein surface, interacting with the aqueous environment.

• Globular proteins: Compact, generally water-soluble proteins with hydrophobic cores and hydrophilic surfaces.

Step-by-Step Guidance

1. Recall that in water-soluble globular proteins, the interior is typically composed of amino acids that avoid water (hydrophobic), while the exterior interacts with water (hydrophilic).

2. Review the properties of the amino acids listed:

   • Glutamine: Polar, hydrophilic

   • Aspartate: Negatively charged, hydrophilic

   • Leucine: Nonpolar, hydrophobic

   • Serine: Polar, hydrophilic

3. Consider which amino acid's side chain is most likely to be buried in the protein core due to its hydrophobic nature.

4. Think about the structure of myoglobin and other globular proteins, and which amino acid would be stabilized in the nonpolar environment of the protein's interior.

Try solving on your own before revealing the answer!