Question

The tertiary structure of a given protein contains an interaction between aspartic acid and lysine.

a. Explain how the structure of amino acids determines the function.
b. A mutation occurs in the DNA of a globular enzyme. If the lysine amino acids were found within the active site of the enzyme, describe the effect this change is likely to have on enzymatic function.
c. If a mutation in the DNA of a globular enzyme changed all of the lysine amino acids to aspartic acid, predict how the relative position of the amino acid in the tertiary structure of the proteins would be affected when the protein is placed in an aqueous solution.
d. Justify your prediction by providing evidence that supports your claim.

Answer 1

A mutation changing lysine to aspartic acid would affect the relative position of amino acids in the tertiary structure of a protein. This change in interaction could alter the overall conformation of the protein. The new interactions might not be as stable, impacting the protein's stability and function.

Step-by-step explanation:

The tertiary structure of a protein is determined by a variety of chemical interactions, including hydrophobic interactions, ionic bonding, hydrogen bonding, and disulfide linkages. One type of interaction that contributes to the tertiary structure is the ionic bonding between oppositely charged side chains of amino acids. In this case, there is an interaction between aspartic acid (an acidic amino acid) and lysine (a basic amino acid).

If a mutation in the DNA of the protein changes all of the lysine amino acids to aspartic acid, the relative position of the amino acids in the tertiary structure would be affected. This is because the interaction between aspartic acid and lysine, which was originally an ionic bond, would now be a bond between two aspartic acid side chains. This change in interaction could alter the overall conformation of the protein.

When the protein is placed in an aqueous solution, the changes in the tertiary structure could impact the protein's stability and function. The new interactions between aspartic acid side chains might not be as strong or stable as the original ionic bonds, potentially leading to a less stable protein structure.