A change in pH is able to cause protein denaturation because
a. The amino group is sensitive to OH-
b. The molecules startmoving so rapidly that they come apart
c. Water is neutral.
d. It causes the areas that were hydrophobic to become hydrophilic
e. The primary structure changes when the [H+] changes
The Correct answer and Explanation is:
The correct answer is d. It causes the areas that were hydrophobic to become hydrophilic.
Explanation:
Protein structure is crucial for its function, and it consists of four levels: primary, secondary, tertiary, and quaternary. The primary structure refers to the linear sequence of amino acids, while the secondary structure involves local folding (such as alpha-helices and beta-sheets) stabilized by hydrogen bonds. The tertiary structure is the overall three-dimensional shape of a protein, which is stabilized by various interactions, including hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bridges.
pH is a measure of the hydrogen ion concentration ([H+]) in a solution. Changes in pH can significantly influence the charge and solubility of amino acids, which in turn affects the protein’s tertiary and quaternary structures. Proteins have specific regions that are hydrophobic (water-repelling) and hydrophilic (water-attracting). When the pH of a solution changes, the ionization state of the amino acids can also change. For instance, the side chains of acidic and basic amino acids can gain or lose protons depending on the pH, which alters their charge and polarity.
As the pH shifts, certain hydrophobic regions of the protein may become hydrophilic if they acquire polar or charged groups. This transition disrupts the non-covalent interactions that maintain the protein’s structure. The exposure of previously buried hydrophobic regions to the aqueous environment leads to protein unfolding or denaturation. Denatured proteins often lose their functional properties because the specific shape required for biological activity is compromised.
In summary, the change in pH causes the areas that were hydrophobic to become hydrophilic, disrupting the protein’s delicate balance of interactions and leading to denaturation. This denaturation can affect the protein’s biological function, highlighting the importance of pH in maintaining protein structure and activity.