What causes changes in the shape of the active site of an enzyme when the $\mathrm{pH}$ changes?

• A. Presence of metal ions
• B. Alteration in hydrogen bonding
• C. Increase in temperature
• D. Addition of a substrate

Answer: (B)

Verified step by step guidance

1. Understand that enzymes are proteins, and their function is highly dependent on their three-dimensional structure, particularly the shape of their active site.
2. Recognize that the active site of an enzyme is where substrate molecules bind and undergo a chemical reaction. The shape and chemical environment of the active site are crucial for enzyme activity.
3. Learn that hydrogen bonding is a key interaction that helps maintain the structure of proteins, including enzymes. These bonds can be sensitive to changes in pH.
4. Explore how changes in pH can affect hydrogen bonding. At different pH levels, the ionization state of amino acid side chains can change, disrupting hydrogen bonds and altering the enzyme's structure.
5. Conclude that alteration in hydrogen bonding due to pH changes can lead to changes in the shape of the enzyme's active site, affecting its ability to bind substrates and catalyze reactions.