What happens to enzymes at very high temperatures or extreme pH?

• A. They become more active at high temperature
• B. They denature and lose their shape and function
• C. They divide into two
• D. They remain unchanged

Answer: (B)

Enzymes rely on a precise 3D shape to form the active site that binds the substrate. At very high temperatures, the energy disrupts the bonds that hold that folded structure, causing the enzyme to unfold. Extreme pH also breaks bonds by changing the ionization of amino acid side chains, so the protein’s shape is altered or lost. With the active site distorted, the substrate can no longer fit, so the enzyme loses its function. Up to a certain temperature and pH, activity can increase, but beyond those conditions the enzyme denatures.