Final answer:
Changing a Glu residue to Aspartic acid would likely result in the least change to the protein's overall structure since both amino acids are acidic and hydrophilic, meaning they have similar properties.
Step-by-step explanation:
If a protein underwent a mutation such that a Glu residue was changed to another amino acid, which of the following amino acids would least likely result in a change in the overall structure of the protein? The options are Proline, Lysine, Aspartic acid, and Valine.
Glutamic acid (Glu) is a hydrophilic amino acid with an acidic side chain, while Aspartic acid (Asp) is quite similar in structure, having a shorter side chain but also an acidic nature. Substituting Glu with Asp may cause the least alteration, maintaining similar charge and hydrophilicity. By contrast, Valine is hydrophobic, Lysine has a long basic side chain, and Proline introduces kinks in protein structure due to its unique cyclic nature. Thus, changing Glu to Proline, Lysine, or Valine would likely cause considerable changes in protein structure.