In a protein engineering project, you need to introduce flexibility into an alpha helix. Which amino acid would you choose and why?

• A. Tryptophan, because its bulkiness increases flexibility.
• B. Glycine, because its small size allows for more conformational freedom.
• C. Proline, because it introduces a kink that increases flexibility.
• D. Lysine, because its charge increases flexibility.

Answer: (B)